Embryo formation week by week. Intrauterine development of the fetus by week. Examination during pregnancy

Pregnancy is a process in which a baby develops from two tiny parental cells. Fetal development by weeks of pregnancy is a fascinating story about what exactly happens at each week of pregnancy, how the weight and height of the fetus changes, what sensations a mother experiences as the gestation period increases. In the article, we will tell you about what interests every expectant mother: when the baby begins to hear her speech, when and how the weight of the fetus changes, when you can take a photo of the fetus with an ultrasound scan, what causes the mother's feelings during pregnancy and much more.

First and second weeks of pregnancy: baby? Which child?

At the time of the appearance of the embryo, the gestation period is already 2 weeks. Why? Let's decide from what we will count the term. There are concepts of embryonic and obstetric term. The embryonic gestational age is the true period from the moment of conception. Obstetric term - from the first day of the last menstruation. The obstetric period is on average 2 weeks longer than the embryonic one. During an ultrasound scan, in the card of a pregnant woman, in the sick-list, the obstetric period will always be indicated by the date of the last menstruation. But from the third week of pregnancy, the development of the fetus actually begins. Below you will find a description of each week of pregnancy: how the fetus develops, what happens to the uterus, how the feelings of the expectant mother change.

3rd week of pregnancy: meeting of parents

At the end of the second and the beginning of the third week (on average, on the 14th day of the cycle), ovulation occurs. At this moment, the woman's egg leaves the ovary into the fallopian tube and where it meets with the sperm in the next day. Of the 75-900 million sperm that enter the vagina, less than a thousand reach the cervical canal. And only one will penetrate the egg.

The sperm and the egg carry half the set of chromosomes of the future human. As a result of their fusion, the first cell of a new organism with a full-fledged chromosome set is formed - a zygote. Chromosomes determine the baby's gender, eye color, and even character. The zygote begins to divide and move to the uterine cavity. The journey to the uterus will take about 5 days; by this age, the embryo will consist of about 100 cells. The next stage is implantation - the introduction of the embryo into the wall of the uterus.

4th week of pregnancy

The ball of cells is officially called the embryo. The size of the fruit at this time is like a poppy seed, about 1.5 mm.

At the end of this week, the mom-to-be notices that the expected period is not starting. On this period a woman may feel drowsiness, weakness, increased sensitivity of the mammary glands, mood swings. A pregnancy test shows a positive result. The test detects the hCG hormone, which begins to be produced after implantation.

The embryonic period lasts up to 12 weeks. The axial organs and tissues of the baby are laid. A yolk sac with a supply of nutrients, an amniotic bladder, is formed, from these extraembryonic organs the fetal membranes and chorion subsequently develop - the future placenta. Below we will analyze what happens in the embryonic period every week, how the height and weight of the fetus changes, and what sensations a woman will experience.

5th week of pregnancy

The embryo consists of three layers - the outer ectoderm, from which the ears, eyes, inner ear, and connective tissue are formed; endoderm, from which the intestines, bladder and lungs will develop; and mesoderm - the basis for the cardiovascular system, bones, muscles, kidneys, reproductive organs.

In the embryo, the anterior and posterior poles are determined - the future head and legs. The body of the embryo is laid along the axis of symmetry - the chord. All organs will be symmetrical. Some are paired, for example, the kidneys. Others grow from symmetrical primordia, such as the heart and liver.

At the 5th week of pregnancy, with a hCG level of 500-1000 IU / L, it is possible to determine a fertilized egg with a size of 2 mm, it is like a sesame seed in size. Each woman experiences this period in different ways, but most develop nausea, drowsiness, odor intolerance - signs of toxicosis.

6th week of pregnancy

Now the baby is no larger than a lentil, at the beginning of the week 3 mm, and by the end - 6-7 mm. The embryo is somewhat similar to a fish and so far little resembles a person. The rudiments of arms and legs appear. When the brushes appear, the legs will still be in the form of rudiments. The cerebral hemispheres are being formed. A small heart pulsates, it is divided into sections.

The future placenta is laid from the chorionic villi, blood vessels are actively growing through which blood is exchanged, and, accordingly, everything necessary for the unborn child between mother and baby.

At this time, the phenomenon of toxicosis may increase, severe weakness and vomiting may appear. Adequate drinking is important during these weeks of pregnancy.

7th week of pregnancy

The embryo is about the size of a blueberry, height 8-11 mm, weight up to 1 g. Hints of a future nose, eyes, ears and mouth appear. A fantastic rate of brain growth is noted - 100,000 cells per minute! Interdigital gaps have already appeared on the handles, but the fingers have not yet been separated. The umbilical cord and the uteroplacental circulation system are formed: the baby's breathing and nutrition comes from the mother's blood.

It is during this period that many expectant mothers often come to the first ultrasound scan during pregnancy. At 7-8 weeks with a CTE (coccygeal-parietal size) 10-15 mm. On ultrasound, a heartbeat is determined with a frequency of 100 to 190 beats per minute, which is significantly higher than that of an adult. At this time, the first photo of the gallery of fetal development is made by week. Without the instructions of a doctor and do not understand where to look. It will be clearer later, especially on a three-dimensional ultrasound.

So far, mom has not noticed an increase in the abdomen, and the gynecologist can already tell about an increase in the uterus. The woman has an increased frequency of urination, which is associated with an increase in the volume of fluid in the body.

8th week of pregnancy

The kid is the size of a bean, from 15 to 40 mm, and weighs about 5 grams. Over the past two weeks, it has quadrupled! The outlines of the face continue to develop, they become more graceful, the upper lip, the tip of the nose stand out, the formation of the eyelids begins.

At the 8th week of pregnancy, ossification of the bones begins - arms, legs, skull. The structuring of the gastrointestinal tract, heart, kidneys, and bladder is being completed.

Somewhere at 7-8 weeks of pregnancy, the baby begins to move, but the mother will not feel these movements in the coming months. Mom's condition practically does not change. It may become easier due to adaptation to the state and awareness of their new role.

9th week of pregnancy

The little man is only about the size of a grape - its length is 35-45 mm, and its weight reaches 10 grams. The reproductive system is laid down, and the adrenal glands are already producing hormones, including adrenaline.

The brain is developing intensively, including the cerebellum, which is responsible for the coordination of movements. Movements become more controlled. The digestive system is actively developing. The liver starts producing new blood cells. The head takes up half of the entire body length. The tiny fingers of the hands get longer.

The amount of circulating DNA of the embryo in the mother's blood is sufficient for a non-invasive prenatal test.

Mom still has symptoms of toxicosis. Usually at this time she turns to a gynecologist to register.

10th week of pregnancy

Do you know such a fruit - kumquat? Here is a baby about this size now. This week it will officially be called a fetus, but for now we call it an embryo. This period is considered the end of the first critical period. Now the dangerous effect of drugs, leading to malformations, is not so significant.

A lot of events are happening these days. The webbing between the toes disappears and the toes separate. Bones harden. The kidneys begin to work, performing their main function - the production of urine. The brain produces 250,000 neurons every minute. A diaphragm is formed between the abdominal and chest cavities.

My mother is experiencing toxicosis. Due to changes in nutrition, metabolism, muscle tone and hormonal surges, the figure and body movements can change. The uterus is about the size of a grapefruit, but the pregnancy is not yet visible to others.

11th week of pregnancy

From 11 to 13 weeks, the baby undergoes a serious medical examination - ultrasound screening. Determine the thickness of the collar space, nasal bones, conduct a study of the vessels, exclude gross changes in the structure of the body. Examine internal organs, structure of the face, brain, arms and legs, spine. Your baby is only about the size of a fig, and the doctor paints the fetal anatomy with such details! The head is still large in relation to the body, but the proportions continue to change: the head is large, the body is small, the upper limbs are long, and the lower limbs are short and bent at the knees. The rudiments of nails and teeth appear.

With the results of the ultrasound, the mother undergoes a biochemical blood test for chromosomal abnormalities and the risk of developing complications of pregnancy.

The symptoms of toxicosis are replaced by new sensations: heartburn, bloating, and there may be constipation. A woman should pay more attention to her diet and fluid intake.

12th week of pregnancy

Your baby is about the size of a lime. Until 11-12 weeks, there are no reliable ultrasound differences between boys and girls. The probability of correctly determining the sex of the fetus is already above 50%. The weight of the fruit is about 20 grams, and the length is about 9 cm.

At this time, the baby begins to actively move his arms and legs, hands, fingers. Due to active growth, the intestines cease to fit in the tummy and begin to fold into loops. During this period, the intestines are trained: the amniotic fluid passes through it, which is swallowed by the fetus. White blood cells appear in the blood - leukocytes, which carry the function of protecting against infections.

Mom's weight gain About the norms of 12 weeks of development and ultrasound of pregnancy - about 1-2 kg. Doctors recommend doing gymnastics for pregnant women, swimming is shown.

13th week of pregnancy

Pea pod - this is how you can describe the size of the baby in household measurements. Or 7-10 cm, 20-30 grams. From the 13th week, the second trimester of pregnancy begins. All the main organs and systems have already been formed, the rest of the time before the birth, the organs will grow and develop.

The face becomes more and more like a human. The ears move closer and closer to their place from the neck, and the eyes from the side to the center of the face. The first hairs appear. 20 milk teeth were formed.

The head is still disproportionately large, but the body will now grow faster. Hands continue to grow, the baby can already reach the face. Often, during an ultrasound scan, doctors show parents how the baby puts a finger in his mouth.

At this time, the shape of the abdomen changes, the old clothes become tight. The surrounding people can notice the new emotional mood of the woman, she becomes more calm and relaxed.

14th week of pregnancy

At 14 weeks, the fetus grows to 13 cm and 45 grams. In boys, the prostate is formed, and the ovaries in girls descend into the pelvis. The palate is already fully formed, active reflex sucking begins. The baby imitates breathing movements in order to effectively take the first breath after birth.

The formed pancreas begins to produce the most important hormone of carbohydrate metabolism - insulin. And in the depths of the brain, the pituitary gland begins to work - the head of all organs of the endocrine system, it is he who subsequently controls all the glands of the body.

The uterus is 10-15 cm above the pubis, the woman herself can feel its upper part. The use of special cosmetics for the skin of the abdomen is recommended.

15th week of pregnancy

The size of the fruit is about the size of an apple, and the weight is about 70 grams. The whole baby is covered with small fluffy hair - they are on the back, shoulders, ears, on the forehead. These hairs help to retain heat. Then, when the baby has accumulated enough fatty tissue, the hairs will fall off. The child makes various grimaces, frown, frown, squint, but this does not at all reflect his mood. He constantly changes his position, actively moving. But the baby is still too small and does not hit the walls of the uterus. There is a unique pattern of skin on the fingertips and special proteins on the red blood cells that determine the blood type.

The mother may have pigmentation on the abdomen.

16th week of pregnancy

The baby's size resembles an avocado. The skeletal bones become harder but flexible enough for the baby to pass through the birth canal. The umbilical cord contains one vein and two arteries, surrounded by a gelatinous substance that protects the vessels from pinching and makes the umbilical cord slippery to move. Girls these days are forming sex cells - your future grandchildren.

Weight gain by this week of pregnancy is 2-3 kg.

17th week of pregnancy

The size of the baby is 12-13 cm and the weight is up to 150 g, the size of a turnip. The arms and legs are commensurate with the size of the body and head. Fat begins to accumulate under the skin, sweat glands develop. The placenta provides the baby with vitamins, minerals, proteins, fats and oxygen by removing waste products.

Due to the increase in the volume of circulating blood, the mother may experience a rapid heartbeat. In this case, pay the doctor's attention to this in order to figure out if everything is in order.

18th week of pregnancy

Your child is the size of bell pepper and weighs 250 grams and is ready to chat. Yes, now the baby can hear, and loud noise can scare him. He gets used to the voice of his parents, and will soon be able to recognize it from other sounds.

Actively developing and functioning endocrine system fetus. There are so many "baby" hormones that the baby can even supply the mother's body.

Mom this week can feel the fetus moving for the first time. While they are weak and infrequent, don't worry if you don't hear your baby too often.

19th week of pregnancy

The growth of the fetus is 25 cm, and the weight is already 250-300 grams.

The creamy lube coats your baby's skin and helps regulate body temperature. The molars are laid, they are located under the rudiments of the milk teeth. The head does not grow so quickly, but the limbs and body continue to grow, so the baby becomes more symmetrical.

The uterus is located 1-2 cm below the navel. Due to its intensive growth, painful sensations associated with stretching of the ligaments of the uterus may occur.

20th week of pregnancy

A satisfied child weighing 240 grams. Especially well at this time, he is given flexion and extension of the arms and legs. He is becoming more and more like his parents.

Week 20 is the equator of pregnancy. The growing uterus compresses the internal organs, so the mother is faced with shortness of breath, frequent urination.

During these weeks, my mother is attending another scheduled ultrasound scan, and Doppler is being performed. This is a good time for ultrasound on video and another photo of the heir.

21st week of pregnancy

The growth of the fetus is 25 cm, and the weight is 400 g. Most of the nutrients come from the placenta. If amniotic fluid is swallowed, the stomach is already equipped to digest it and receive nutrients. The kid begins to feel the taste.

The mother gains more weight as the baby grows intensively.

22nd week of pregnancy

By the end of the week, the baby will be about 500 grams. The skin ceases to be translucent, but remains red and wrinkled and covered with grease. Nerve endings ripen, and the baby becomes sensitive to touch. From 21 to 25 weeks, the brain increases 5 times - from 20 to 100 grams!

23rd week of pregnancy

Billions of brain cells will develop over the next few weeks. Their job is to control all of your baby's movements, senses, and basic life functions such as breathing.

The lungs begin to produce a substance that allows the lungs to swell and fill with air after birth, and the fetus begins to "breathe". The respiratory rate is 50-60 per minute.

The height of the uterine fundus is 4 cm above the navel. The uterus grows, which can cause discomfort in the spine, joints, so a special bandage may be required.

24th week of pregnancy

The kid is still small, his weight is 600 g, and his height is about 33 cm. The child actively reacts to the appeal to him. The inner ear is already fully formed (vestibular apparatus), he began to understand where is the top and where is the bottom, movements in the uterine cavity become more meaningful.

Mom adds about 500 grams per week. Swelling of the feet may occur, so it is important to choose comfortable shoes and rest your feet.

25th week of pregnancy

The growth of the fetus is 30-32 cm, weight 750 grams. In the large intestine, meconium forms - the first stool of the baby, which will completely pass within a few days after birth. The osteoarticular system is actively developing, bones are strengthened.

Mom may feel signs of anemia (anemia) due to iron deficiency. Fatigue, pallor, fatigue and tachycardia are a reason to consult a therapist and take blood tests for anemia.

26th week of pregnancy

Height 34 cm, weight 900 grams.

The lungs are actively developing, they are filled with a special substance that will not allow the lungs to stick together after the first breath.

The child has distinct periods of sleep and wakefulness. Mom senses his activity by moving in the abdomen. If you are lucky, you and your baby will have the same sleep and activity periods.

27th week of pregnancy

The body weight of the fetus is already about a kilogram, and the height is 34 cm. Growth hormone begins to be produced in the pituitary gland. And the thyroid gland contains hormones that regulate metabolism.

Due to the involuntary contractions of the diaphragm, the mother may feel the baby's hiccup-like movements. In adults, such movements are accompanied by the closure of the vocal cords, so there is a characteristic “hiccup” sound, while in a baby this space is filled with liquid before delivery, so this “hiccup” is silent.

There may be new sensations in the legs - tingling, goose bumps or even cramps. This is a reason to consult a doctor for an additional examination and prescription of treatment.

28th week of pregnancy

Now your baby begins to close and open his eyes, which until this moment were not completely closed. The iris is colored by pigment, although this coloration is not final. Up to a year in children, eye color may change.

At 28 weeks, in case of multiple pregnancies, the mother receives “ sick leave". The weight gain by this time is 7-9 kg. At this time, Rh-negative mothers are injected with immunoglobulin.

29th week of pregnancy

The child is 36-37 cm long, weighs about 1300 grams and becomes stronger and more active. We can say that he also shows character. A child reacts differently to different foods, sounds, light.

The woman suffers from heartburn, heaviness after eating. There may be increased urination or even false urge.

30th pregnancy

In the coming weeks, your baby will be actively gaining weight. Adipose tissue will perform the function of thermoregulation after birth, provide energy, and protect organs. The baby's movements will become less active, which is associated with an increase in its size. But if you do not feel any shock as usual, be sure to tell your doctor. Pregnant women may feel breast swelling and colostrum secretion.

At this time, a certificate of incapacity for work in case of singleton pregnancy is issued.

From 28-30 weeks of pregnancy, regular CTG (cardiotocography) begins to assess the condition of the fetus. With CTG, fetal heartbeat, uterine tone and physical activity.

31st week of pregnancy

Before birth, the little man will be in the position of an embryo, because otherwise he will no longer fit in the uterine cavity, his weight is 1600 g, and his height is already 40 cm.

These days, an important event occurs in male fetuses - the testicles on the way to the scrotum. The girls have a practically formed clitoris.

Weekly weight gain - 300-400 grams. At these periods, edema and increased pressure may appear, which may be a symptom of a formidable complication - preeclampsia. Therefore, the expectant mother should be as attentive as possible to any changes in well-being.

At a period of 30-32 weeks, an ultrasound of the third trimester is performed with Doppler analysis - an assessment of blood flow.

32nd week of pregnancy

This is an important week, another critical time has passed. Babies born at this time are healthy and fully functional. All major organs are fully functional by this week, except for the lungs, which take a little longer to fully mature.

The expectant mother may experience pain in the joints, pubic articulation. Wearing a bandage, swimming can alleviate these phenomena.

33rd week of pregnancy

It is more and more difficult for the baby to move, he is already 44 cm and weighs about 2 kg. Many babies like to live in the rhythm of their mother: sounds, food and walks can affect the child's activity.

The height of the fundus of the uterus is 34 cm from the level of the pubis. It becomes more difficult for mom to walk or exercise a lot, she needs a break.

34th week of pregnancy

Within a few weeks, your boy or girls will begin to prepare to meet their parents. The original white lubricant that covers the skin begins to thicken, accumulating in the axillary and groin folds, behind the ears. At the time of the newborn's first toilet, the lubricant will be removed. Height 47 cm, weight 2200-2300 g.

Pregnant women begin to feel false contractions - preparing the muscles for the process of childbirth.

35th week of pregnancy

The fetus is preparing for birth, finally taking the correct position, upside down. This is how about 97% of children are located. The remaining 3% can take a position with the pelvis down or even transverse. Fetal growth 47-48 cm, weight 2300-2500 g.

Almost all expectant mothers experience shortness of breath during this period.

36th week of pregnancy

The baby continues to store fat, which is critical after birth for energy and warmth. The sucking muscles are ready to go: after birth, the baby will be hungry and will ask to feed him for the first time.

The height of the bottom of the uterus is 36 cm. Hormonal changes in the woman's body begin to prepare for childbirth - oxytocin and prostaglandins are produced.

37th week of pregnancy

The movements of the fingers become more coordinated, soon he will be able to grab your finger. The accumulation of subcutaneous fat continues, its volume is approximately 15% of the baby's weight. Height 48-49 cm, weight 2600-2800 g. The vellus hair, covering the body, gradually disappears.

The pregnant woman feels the harbingers of childbirth - the lowering of the fundus of the uterus, a decrease in the volume of the abdomen, loosening of the stool, increased training contractions, the discharge of the mucous plug.

38-40 weeks of pregnancy

In obstetrics textbooks, 38 weeks were the term for full-term pregnancy. If your baby is born right now, it will be a full-term pregnancy, and the baby will not have any risk factors associated with the birth. ahead of time... Everything further developments aimed at preparing for childbirth.

Discharge of the mucous plug should be distinguished from leakage of amniotic fluid. If there is too much discharge, see your doctor for a special test.

In most cases, the baby's head sank into the pelvis at 38-39 weeks, this is called cephalic presentation. If the child lies straight with his head down, this is called a longitudinal position, if a little at an angle, then oblique. There is also the concept of fetal position: I position means that the back is turned to the left uterine wall, and II - to the right. How the fetus is located will be told on an ultrasound scan.

At birth, doctors assess the child's condition according to several parameters: activity, muscle tone, heart rate, respiration, skin color, reflex reactions. The more points, the healthier your baby was born.

So we ended our journey after 40 weeks of fetal development during pregnancy. The most important thing is to be attentive to yourself and the words of your doctor, the appointment of tests and ultrasound, pay attention to all the sensations and enjoy pregnancy and future motherhood.

Knowing how the fetus develops by weeks during pregnancy, you can control the health of the mother and baby. The doctor monitors whether the woman's physical and psychological sensations match the norms. This allows you to react in time and help mom and baby, if necessary.

An expectant mother is calmer if she knows that changes in her body are going according to plan. It is useful to know how the fetus develops by the weeks of pregnancy. So mommy knows in advance what to expect, what to prepare for. Can tell the doctor if something goes wrong.

How to correctly determine the onset of pregnancy

To track pregnancy week by week, fetal development and sensation, you need to know when to count down. How the onset of pregnancy is determined:

• if the mother knows when conception occurred, this is the most accurate option;
• the period of pregnancy is determined by the doctor when he determines the size of the uterus, but in the first weeks it will not work to set the period in this way, the uterus is still too small;
• by the date of the first day of the last menstruation, the date of conception is determined quite accurately, from this time the uterus begins to prepare for pregnancy;
• from 4-5 weeks, you can conduct an ultrasound examination, it allows you to very accurately determine the duration of the crumb in the tummy.

Consider how the fetus develops by weeks of pregnancy, a description of the changes in a small organism. We will tell you all about pregnancy by week.

Fetal development by weeks of pregnancy (photo)

Week 1

Obstetric week is not counted from the moment of conception, but from the last day of menstruation. At this time, the body is only preparing for a possible conception. If fertilization occurred during this period, a slightly smearing spotting may be observed.

2 week

This time is considered the most favorable for conception. If a woman's body is healthy, there are no pathological processes, then by the second week of the cycle, the egg matures and is ready for fertilization. If conception has occurred, then at this time the ovum attaches to the uterus, from this moment the development of the fetus begins.

3 week

The embryo is still tiny, it is fixed in the uterus, the formation of sexual characteristics is laid at the cellular level. The placenta begins to form.

4 week

At this time, pregnancy can be determined by tests. The size of the embryo is no more than a poppy seed, weighing about 0.5 g. The cells divide every minute, the crumb grows. Mom's mood can change dramatically during this period. Drowsiness is common. Increased sensitivity to odors appears. In the morning, nausea, dizziness may appear.

5 week

The baby at this time is a bit like a tadpole: he has a small body and a large head. Its size is about 1.7-2 cm. The spinal cord and brain are being laid. In the fifth week, the baby has a blood group. The thyroid gland, intestinal and urinary systems begin to form. The baby's tiny heart begins to beat.

6 week

The head and body of the future baby are clearly visible. Tiny outgrowths appear - legs and arms. Hormonal changes in the mother's body lead to the fact that hunger can often be felt or, conversely, an aversion to food appears. During this period, the expectant mother may lose weight due to the onset of toxicosis.

7 week

The placenta is fully formed: it performs protective and nutritional functions.

Baby development:

• the body is about the same size as the head, while there is still a small tail on the tailbone;
• the nervous system is formed, both hemispheres of the brain are already formed;
• the heart works, it consists of 4 chambers;
• blood circulation improves, the placenta feeds the baby with oxygen, supplies nutrients, it protects him from microbes, bacteria, infections and toxins;
• the skeleton tissue turns into bone, the musculoskeletal system is formed, the crumb can bend the elbows and knees;
• the hearing system is formed, the rudiments of the teeth are laid, a nose, nostrils, and upper lip appear;
• the upper covering layer appears - the epidermis;
• a mound appears between the legs, along which it will later be determined who is in the tummy: a girl or a boy.

8 week

By this time, almost all the systems of a small organism have been laid down and their rapid development is underway. The tail is no longer visible. The kid can move the arms and legs, open his fingers. The eyes are now closer to each other, the visual system is being formed. At this time, the baby is already able to respond to touch.

9 week

The arms and legs are well formed, the baby can move around in the amniotic fluid, he is still small and has not taken up all the space. The genitals are traced. The crumbs have formed eyelids and can involuntarily blink. The weight of the fetus is about 4 g, the height is about 3 cm.

10 week

The brain continues to develop. The head gradually rises from the chest. The fingers are lengthened, although the membranes between them still remain. Sex hormones begin to be released, in boys - testosterone, in girls - estrogen.

11 week

The baby's weight is about 11 g, and his height is about 5-6 cm. Auricles are formed, hair follicles are laid.

12 week

The fruit is about the same in length, by weight - about 12-14 g. The intestines begin to contract, the gastrointestinal tract is trained. The toddler tries to raise his head and may begin to suck his thumb. He already responds to sounds and is sensitive to pain.

13 week

The vocal cords are formed, the trunk begins to grow actively, and the growth of the head slows down. The sense of smell develops. There are reactions to changes in temperature, light, noise, music. The baby can already sleep for several minutes a day. The brain can give commands for reflex movements. Villi appear in the intestines. The skin is thin. Weight - about 20 g, height - up to 8 cm.

14 week

The baby's weight is up to 50 g, height is up to 10 cm. The modes of wakefulness and sleep appear. Training in progress respiratory system... Insulin begins to be produced. The baby's heart reacts to mom's stress, so you need to learn to be calm for yourself and your baby.

Pregnancy by week (fetal development with photo)

15 week

Vision is formed, now the baby will be able to see after it is born. He distinguishes between light and darkness. Sweat glands work. Hair begins to break through. The process of ossification of the skeleton has begun, it will require a large amount of calcium from the mother.

16 week

Now the fetus has taken on all the shape of a baby. The skin is still thin, it is covered with a light fluff, and the vessels are clearly visible under it. Fetal weight - 110 g, height - 11-14 cm.The blood changes chemical composition, lymphocytes, erythrocytes, platelets appear. Hemoglobin synthesis is in progress. Eyebrows and eyelashes are visible on the face. The whole body of the fetus is covered with white lubricant, it protects the baby's skin until the very birth.

17 week

The crumb sleeps more and more. When he wakes up, he can stretch. The kid is very sensitive to sounds. Sounds harsh and loud are unpleasant to him. And his mother's voice calms him down. In girls this week, internal reproductive organs begin to form. This week, the strength of the baby's pushes increases, they are frequent and tangible.

18 week

You can already feel the first tremors of the baby. His musculoskeletal system is actively developing. Subcutaneous fat is gradually formed, muscles continue to develop, and the skeleton is more and more strengthened. The weight of the crumb is about 150 g, the height is up to 14 cm.

19 week

The kid sleeps up to 16-18 hours a day. The main senses are improved. The amount of subcutaneous fat increases. The respiratory system develops and strengthens. Weight reaches 200 g, height - up to 14-15 cm.

20 week

On the ultrasound, you can see the sex of the baby, his face, facial expressions. The kid is already yawning, tumbling, playing. The legs have become longer and more proportional, the head is now smaller in comparison with the body. The skin is denser: now it consists of four layers. Marigolds appear on the arms and legs. The head is covered with the first hairs.

21 week

When the baby moves, this can be seen on the surface of the tummy: bumps appear on it. Baby weight - up to 330-350 g, height - up to 26 cm.

22 week

The kid sleeps a lot, and even in a dream he actively rolls over. The nervous system is improving, neurons are fully formed. Weight - about 410 g, height - up to 28-30 cm.

23 week

The baby has a phase of REM sleep - now he can see dreams. The respiratory organs are not yet formed, but the baby begins to do the first trial exercises. Weight reaches 400-420 g.

24 week

Height - up to 25 cm, weight - up to 500 g. Oxygen enters through the umbilical cord, but the baby already knows how to inhale and exhale. The brain is formed, neural connections increase. The kid plays with the umbilical cord, makes grimaces, frowns and sucks his thumb.

25 week

The production of pigment begins in the child's hair. The kid can clench his hands into fists. He has a grasping reflex. Crumb weight - 700 g, height - about 30-35 cm.

26 week

The child is gaining weight, now he is about 1 kg, his height is 33-35 cm. Subcutaneous fat accumulates, the skin brightens. The baby becomes stronger, his kicks can cause discomfort to the mother.

27 week

The child's brain grows, develops. The foundations of thinking are laid: memory and attention. Calcium is still needed in sufficient quantities, because the bones have not yet fully formed. There is an accumulation of subcutaneous fat and a change in skin color. The placenta forms the child's first immunity, which will protect him for the first six months.

28 week

Subcutaneous fat accumulates, folds are smoothed out, the skin brightens. In the brain, convolutions are laid, there is a bookmark and growth of intelligence, emotions appear. This week, the Rh-conflict between the fetus and the mother is possible, so the doctor closely monitors this process and, if necessary, takes special measures. The baby's weight is about 1.3 kg, his height is up to 37 cm.

We will tell you in detail what will await you from the beginning of the birth of a new life to the very birth.

Pregnancy is a special time that changes the outlook of the expectant mother, her values ​​and priorities. Almost every woman faces certain difficulties while carrying a baby. To avoid them, it is important to have complete information about all the processes occurring in the female body at every stage of pregnancy.

Early pregnancy: first month

Most women do not even assume that they are in a position, while very serious changes are taking place in their body. Pregnancy becomes known only by the end of the first month, and sometimes by the beginning of the second.

Doctors consider the beginning of pregnancy from the beginning of the last menstrual period, although fertilization usually occurs after ovulation. Therefore, the concept of "obstetric term" for several weeks exceeds real time gestation.

Changes in a woman's body

The first and second weeks of the month are the time when a woman is not actually pregnant yet, but her reproductive system is actively preparing for conception. In the first week, as usual, menstruation passes. If you are just planning to become a mother, then you should stop taking analgesics for menstrual pain: the chances of successful conception will be higher. In the second week, one of the eggs begins to mature.

By the beginning of the third week, at the moment, the strongest egg leaves a special bladder filled with liquid into the fallopian tube. Here the female reproductive cell will remain for several days, waiting for fertilization.

The so-called corpus luteum will begin to form. It will be responsible for the hormonal balance that is optimal for the development of pregnancy.

All that is needed now is fusion with the sperm. Two cells, connecting with each other, form a zygote - a future embryo. The zygote is miniature in size and moves freely along the uterus, attaching itself to its wall only after a few days.

To maintain the life of the zygote, the mother's body produces a large amount of progesterone. Because of it, a woman will feel heaviness in the lower abdomen and pain in the nipple area, like with PMS. The urge to urinate will become frequent, drowsiness and sensitivity to odors may appear.

Baby development at 1 month

In this early period, all the genetic information is laid that forms the appearance, character traits and predisposition to diseases of your baby.

The gender of the crumbs is also determined. Sperm are of two types: one carries the XX chromosome, the other carries the XY chromosome. The sex of the child will depend on which of them can get to the egg. If the fusion occurs with the XX sperm, the female embryo will begin to develop; if an XY sperm gets into the fallopian tube, the couple will have a boy. By the end of the 4th week of pregnancy, the embryo has already completed attachment to the uterine cavity and enters the embryonic stage.

The level of the hormone will increase, and now pregnancy can be determined using a simple pharmacy test.

Three areas are laid in his body, which will later become full-fledged organs and systems. Also this week, the formation of the chorion (future placenta) and amnion (fetal membranes) is completed. And your baby is still very small - the size of the embryo is only 0.5 millimeters.

1. It is necessary to undergo an ultrasound scan as soon as there is a suspicion of a conception that has occurred. This will help diagnose an ectopic pregnancy in time.
2. At this time, it is useful to take vitamins A and E. Also, all pregnant women are prescribed folic acid for the proper development of the fetus.
3. Complete rejection of tobacco, alcohol and junk food is required. The expectant mother needs to walk in the fresh air as much as possible and get pleasant emotions.

Second month of pregnancy: changes in a woman's body

At this time, the fact of pregnancy is already clearly established. There is a delay in menstruation, there should be no discharge. Any discharge with bloody impurities speaks of the danger of embryo rejection, and in this case, a visit to the doctor is required.The first signs of early toxicosis appear. It is especially expressed in morning sickness and vomiting.

There are problems in the digestive tract: heartburn, belching, constipation. These phenomena will stop only by the end of 3 months.

Psychological changes will be a serious test. Your family should be sympathetic to mood swings. But a pregnant woman should also try to control herself, because nervous tension is not beneficial either for you or for the baby.

The development of the corpus luteum reaches its peak, and the uterus by the end of this month will grow to the size of a large orange and is perfectly palpable on examination.

Due to sprains, a woman may experience pulling sensations in her sides and lower back.

Together with progesterone, lactogen, a hormone responsible for the development of the placenta, begins to influence the body. Their action reduces protein synthesis while increasing the production of glucose and fatty acids. This is necessary to compensate for the expenditure of energy for the development of the fetus.

Baby development at 2 months

In this month, all organs and systems of the crumbs take their place. By the 5th week, his heart will make its first beats, blood vessels will appear. The organs of the respiratory and excretory systems will be formed. The brain is already starting to respond to primitive reflexes.

The embryo still has a small tail, making it look like a small tadpole. The rudiments of facial features will appear on the fetus's head: nose, eye sockets, ears.

In boys, the penis and testicles are determined. Now your future baby has passed from the embryo stage to the fetal stage. Its physical dimensions are about 2.5 cm.

Seventh and eighth months of pregnancy

There is less and less time left until the moment of childbirth. Expectant mothers go on maternity leave, are in search of a good obstetrician and maternity hospital. It is also worth deciding if you want your husband to be present during labor.

Feelings of a woman at 7 and 8 months

The production of the hormone relaxin is increased, which prepares the ligaments of your muscles for childbirth. Because of this, back pain appears, it becomes more difficult for muscles and joints to be in good shape. Your gait may become a little awkward, varicose veins increase, and urinary incontinence is possible.

Also, the action of hormones enhances the growth of body hair. After giving birth, they should disappear, so now it is not necessary to deal with excess hair.

By the end of the 8th month of pregnancy, the belly increases to almost its maximum size. Now the height of the fundus of the uterus will be up to 40 cm. Training (false) contractions begin, which do not cause pain at all. They prepare the uterus for real labor.

In many pregnant women, the nesting reflex is activated. You will more and more want to devote time to bringing comfort in the house, willy-nilly you give preference to viewing and reading materials for pregnant women.

Child development at 7 and 8 months

Your baby has become very large, it is getting closer and closer in the uterus. The fetus occupies a position that will persist until the very birth. If the presentation is unfavorable, you can perform special exercises to help "turn over" the baby.

All basic reflexes have already been formed. Bones are strengthened, the calcium content in them increases significantly. The lungs are fully prepared for the first breath.

By the last week of 8 months of pregnancy, the fetus will weigh twice as much as at the end of the second trimester - 2.5 kg.

1. The most dangerous thing that can happen now is the development of gestosis. If you are worried headache, swelling has increased and blood pressure has increased sharply, it makes sense to urgently go to the hospital.
2. Once every two weeks, you will visit a doctor and have tests. A complete examination is required: measurement of the fundus of the uterus, fetal heartbeat.
3. Swimming can help reduce the feeling of heaviness. They have a relaxing effect on muscles and also calm the nervous system.

The ninth month of pregnancy: a woman's feelings

You have reached the home stretch! Although there is anxiety before childbirth, this month is the easiest for many mothers. It will literally become easier for you - the stomach will lower, which means that the pressure on all internal organs will decrease.

Now your difference in weight with a "pre-pregnant" state is from 8 to 16 kg. The abdomen will no longer increase, on the contrary, visually it may become smaller. This is due to the depletion of amniotic fluid. You will experience for yourself what the harbingers of childbirth are. They will appear several weeks before childbirth (sometimes precursors appear several days before labor). Among them - the strengthening of false contractions and the discharge of the mucous plug.

The problem of constipation disappears, but with pressure on the bladder, a constant urge to urinate begins.

Fetal movements are less noticeable.

Your mental attitude also changes. You will be characterized by slowness and absent-mindedness. Mood swings are the result of anxiety before childbirth. Unleash your emotions, have fun or cry. Communicate more with your loved ones in the last weeks before the hospital, because it is so important for you to feel their care.

Baby development at 9 months

The baby takes the final position in which he will pass through the birth canal. His skin has a light shade, the fluff disappears, and the grease remains in the folds of the body. The bones of the crumbs are quite hard, there is a fontanelle between the seams of the skull. It will overgrow soon after giving birth. Thanks to the fontanelle, it will be easier for the child to be born - the bones of the skull will be in a free position.

The child is completely ready for life outside the mother's womb. The lungs are ready to open at birth, the heart adapts to work in a new rhythm.

In the intestines of the newborn, there is the original feces (meconium), consisting of the remnants of substances from the amniotic fluid.

1 In the last week of pregnancy, the mother needs to be very careful. It will be difficult for you to move, so you need to walk with support if possible. Walk up the stairs holding tightly to the railing.

2 Labor activity can begin at any time. You should always have your personal doctor's number close at hand.

Do not leave the house for a long time, or even better - walk only in the company of loved ones. Always carry with you the package of documents required for the maternity hospital.

3 Take up the collection of bags in the maternity hospital in advance at the beginning of the month. This will make sure you haven't forgotten anything important in your rush.

So, the difficult time of pregnancy has come to an end. Now a new period is beginning, full of completely different worries and joys. Maintain a positive attitude and you will certainly become the best mom!

Read

A woman was created by nature in such a way that at least once in her life she can give the world a new person. The period of expectation and childbirth is the brightest and at the same time alarming time. But the expectant mother shouldn't worry in vain. She should know that a normal pregnancy is the key to the correct development of her child.

If a woman has a clear idea of ​​how the baby's body is formed throughout pregnancy, then it will be quite simple for her to do everything necessary to avoid the development of pathologies.

Should a woman know how her baby is developing?

Knowing how the intrauterine development of the fetus occurs week by week, the expectant mother can correctly organize her nutrition and daily routine. Also, having complete information about what changes are considered the norm, a woman will avoid a state of unreasonable anxiety.

Calculating the intrauterine development of the fetus by week, it should be noted that it lasts 40 of these calendar periods. In other words, a woman's pregnancy lasts 280 days. During this time, the child undergoes a complete process of formation and development of all organs and systems.

Doctors-gynecologists consider the intrauterine development of the fetus by weeks and by periods, of which there are two: embryonic and fetal.

The first lasts from the moment of fertilization of the egg until the 8th week of pregnancy. During this period, after fertilization, an embryo is formed, which descends into the cavity and attaches to it. The fetal period lasts from the beginning of the 9th week until the moment of delivery. The embryo transforms into a fetus, develops and grows.

The division of pregnancy into trimesters is also common:

• First trimester (1 - 12 weeks).
• Second trimester (13 - 27 weeks).
• Third trimester (28-40 weeks).

Now you can consider in more detail how the intrauterine development of the fetus occurs by week.

What happens during the embryonic period?

The most important of this developmental period is the formation of the embryo. Over time, he begins to take on the shape of a person. The embryo is formed from the moment the egg is fertilized. This usually occurs in the fallopian tube.

From the moment of fertilization of the egg, the development of the fetus begins.
By weeks of pregnancy, a morula is formed in the first seven-day period. It is a multicellular organism, the prototype of the embryo. The morula attaches to the wall of the uterus, and the umbilical cord and the outer membranes of the fetus are formed from its outer cells. From the cells that are located inside it, the organs and tissues of the unborn child are formed.

What does a woman feel?

In the first week of pregnancy, a woman has a slightly increased body temperature, it is close to 37˚С. There are no hormonal changes in the body yet, but the expectant mother instinctively feels the changes taking place. From this point on, a woman should be very careful about her diet and lifestyle, exclude bad habits and follow the doctor's recommendations.

Each expectant mother will be very interested in how the fetus develops by weeks of pregnancy. This information will help a woman prevent many dangerous conditions... The third week of pregnancy is alarming because it is during this period that there is the greatest risk of fetal rejection. The woman's immune system tries to reject the embryo. However, in response, a special protein is released that suppresses this protective reaction, and the unborn child has a great chance of survival.

What happens to the embryo in the first weeks of pregnancy?

This period is also characterized by the formation of the placenta. Future child at three weeks is a sphere with a diameter of 0.2 mm. But during this period, the lungs and respiratory organs, the cardiovascular system, the spinal cord and the brain are actively formed, and the baby's face and gender are also laid.
The woman begins to feel mood swings, drowsiness and fatigue, early toxicosis may occur.

Further development of the fetus (this is the fourth week of pregnancy) is very intensive. The unborn child forms three germ layers:

• endoderm - the basis for the development of internal organs;
• mesoderm - what the skeleton and bones will be formed from;
• ectoderm is a material for the formation of the nervous system.

The embryo already has a pulsating tube that turns into a heart. On an ultrasound, a heartbeat is heard during this period. The respiratory organs, the brain continue to form, the face is more clearly outlined. The embryo has limbs, and by the end of the week they are already bent. The embryo is located in the placenta and maintains contact with the mother through this organ.

His heart is already beating!

During this period, many women only find out about their pregnancy, especially if it is the first one. Having found out this fact for herself, the expectant mother is interested in the main question: how does the fetus develop?

By weeks of pregnancy, this is the fifth calendar period. At this time, the embryo still has little resemblance to a person, but his heart is already beating, gender is clearly defined, kidneys, liver, pancreas and thyroid glands are being formed.

Already at the 8th week, the future baby acquires the outlines of a person, his height is 3-4 cm. He has already formed arms and legs, his forehead is clearly visible, the outlines of his eyes, lips and nose are outlined. Internal organs are actively formed and developed. The stomach is already capable of producing juice, the heart is formed, the intestines are growing, the trachea and bronchi have appeared. The spine, brain and limbs are actively developing.

By the end of the eighth week of pregnancy, the embryonic period of development ends, but the first trimester is still ongoing. The unborn child has already acquired a human appearance, the placental-uterine circulation has been formed.

Fetal period

This stage begins from the 9th week of pregnancy and lasts until the very birth. The fetal period is divided into two parts:

• early (9 - 28 weeks);
• late (29 - 40 weeks).

In the early fetal stage, fetal development continues. By weeks of pregnancy, this is the ninth. At this time, the growth of the fetus is 40-50 mm. He begins to be active: bends his arms and legs, turns his head, brings his fingers to his mouth. But my mother is not yet able to feel this, the fetus is still too small.
Outwardly, the future baby looks like a man with a big head. The eyes are still closed, and the skin is transparent. The genitals begin to form, and this process will continue for the 20th week. The cerebellum and pituitary gland develop. The heart has four chambers. The tail disappears, being replaced by the tailbone.

The embryo turns into a fetus

In the tenth week of pregnancy, the embryo is already called the fetus, and weighs 5 grams. In his photographs, isolated fingers, neck, elbows, knees, eyelids and upper lip are already visible.

The tongue has taste buds, the thickness of the umbilical cord increases.

The eleventh week of pregnancy is characterized by the further development of the fetus. He already has eyelashes and milk teeth. The rectum is formed. The spinal cord is already producing red blood cells. The intestines are ready to go.

Many mothers during this period are sent by a gynecologist for a planned ultrasound scan. Undergoing this procedure, women are interested in the main question: is the development of the fetus normal?

In the weeks of pregnancy, the twelfth period begins. During this period, the child has formed phalanges of fingers and earlobes, he opens and closes his eyes. The intestines are already contracting, and the liver is able to secrete bile. The baby's circulatory system is functioning, leukocytes appear.

At the twelfth week, the first trimester of pregnancy ends and the second begins.

The kid is actively growing

During this period, all systems of the fetus are formed, they are developing and growing. At the thirteenth week, which marks the beginning of the second trimester, the baby reaches 80 mm in length and weighs about 20 g. At this time, the fetus is intensively forming a skeleton, the pancreas begins to produce insulin.

The gynecologist will send the expectant mother to the first genetic study. After examining the results of the ultrasound, the doctor will be able to tell you how the intrauterine development of the fetus occurs by weeks of pregnancy, whether the indicators are normal.

At the 14th week, the child's face continues to form, facial expressions, eyebrows and hair on the head appear. On the body of the fetus, fluff and cheese-like grease are formed. The thyroid gland begins to work, its own hormonal background develops.
The excretory system is functioning, the child makes breathing movements.

In the antenatal clinic, you probably saw a stand showing the intrauterine development of the fetus by week.

A table with this kind of information will be useful to every woman.

At the fifteenth week of pregnancy, the child develops hearing, the intestines form the original feces, and the placenta thickens. The fruit weighs about 50 g and is 60 mm tall.

The expectant mother feels the first movements of the baby

The sixteenth week of pregnancy is marked by an increase in the volume of amniotic fluid. The child is actively moving, and the mother begins to feel it. The muscles on the face are developed and the child is characterized by facial expressions at this time. Bones and nails are almost completely formed, the skin is very thin and blood vessels are clearly visible through it.

During this period, the gynecologist directs the woman for a second genetic screening. For this, the expectant mother will have to undergo a second ultrasound scan. It clearly shows the intrauterine development of the fetus by week. Photos that can be taken at this stage are presented below.

We count fetal movements

From the 28th week of pregnancy, the third trimester begins, and from the 29th - the late fetal period. At this time, the child is cramped in the womb, and his movements are not so active. Nevertheless, a woman should clearly track the tremors, their number should be at least 10 per hour. The brain is actively developing, and furrows appear on it. The teeth are covered with enamel, the eyes are capable of focusing. The baby's weight is about 1250 g, and his height is 37 cm.

At the 30 - 31st week of pregnancy, the baby already takes the final position in the uterus. The fetus is actively gaining weight by increasing muscle mass and subcutaneous fat. If a child is born during this period, he has every chance of survival.

Further intrauterine development of the child (by weeks this is already the 32nd calendar period) is characterized by the improvement of the immune and nervous systems. The child has its own routine of waking and sleeping, it has its own temperament. The baby weighs 1800 g, and his height is 42 cm.

At the 33rd - 34th week of pregnancy, the baby actively trains the lungs, perceives the entire environment to the fullest. The skin of the fetus becomes smooth, the bones of the skull harden.

The baby is preparing for birth

At 36 - 37 weeks of gestation, the fetus prepares for birth. His mother’s stomach is already cramped for him and it’s more and more difficult for him to move.

His body has enough fat reserves for thermoregulation after birth, the lungs are ready to breathe. The fluff on the body is already absent, but the hair on the head and nails grow back.

At 38 - 40 weeks, all mothers are expecting childbirth. This can happen at any time. The baby sinks and it becomes easier for mom to breathe. The woman carefully monitors the discharge of the mucous plug and the appearance of contractions.

And finally, it happened! Mom and baby are now together. The crumb is still very small, but full of strength for the knowledge of the new world. Now his status is newborn.

Table of intrauterine development of the fetus by weeks of pregnancy

This article provides a full description of how the intrauterine development of the child takes place by week. The table below will serve as a kind of conclusion to all of the above and will serve as a reminder for the expectant mother.

Intrauterine development of the fetus by weeks of pregnancy

Pregnancy period in weeks	Fruit length, cm	Fruit weight, g	Development of organs and systems
4	0,1		Fertilization of the egg, its implantation, embryo and organ rudiments.
5	0,15 - 0,2		Bookmark of the liver, pancreas, upper respiratory organs, heart.
6	0,4 - 0,6		The appearance of the rudiments of the limbs, listening to the heartbeat, the neural tube closes, parts of the larynx and middle ear are formed.
7	0,7 - 0,9		The trachea, esophagus, small intestine, adrenal glands and sternum develop. The brain is actively forming.
8	0,9 - 1,2		The embryo has a clearly distinguished body and head, equal in size. The rudiments of the nose, eyes, mouth and organs of the reproductive system are formed.
9	1,3 - 1,5	1	The cerebellum develops, fingers are formed on the limbs.
10 - 11	2,7 - 3,5	4	The joints, upper lip, auricles, external genitals, rudiments of milk teeth develop.
12	9	20 - 25	The face is formed, the intestines contract, the liver produces bile, the child moves.
13	10	28	The limbs are fully formed. The pancreas produces insulin.
14 - 15	12,5	50 - 90	The excretory system is active, the child produces urine.
16	16	120	We distinguish the sex of the fetus. The skin is very thin, muscles are formed. The child does not move so chaotically, the mother feels the first tremors.
20	25	280 - 300	On the baby's skin there is fluff and cheese-like lubricant. The intestine forms the original feces. The child is able to hear.
24	30	600 - 800	The work of the kidneys is activated, the fetus is dynamically gaining weight.
28	35	1200	The muscles and reproductive system of the child are being formed.
32	40	1500 - 1600	There is an active development of the senses and the nervous system: the baby is able to see the light and feel the taste.
36	45	2400 - 2500	The child quickly gains weight, his activity decreases.
40	50-52	3200 - 3500	The baby is ready for birth.

Of course, it is best to study this information when a pregnancy is just being planned. Then the woman has more chances to properly organize nutrition, regimen, intake of necessary vitamins and minerals. However, information about the intrauterine development of the baby will always be timely and interesting for the expectant mother, regardless of the length of her pregnancy.

Pregnancy is a physiological process of the development of a new organism. An embryo (fertilized egg) develops in the uterus, which then becomes a fetus. Pregnancy lasts 9 astronomical months (10 obstetric). Consider the development of a child by week.

Fetus or embryo

In medicine, there are often two concepts regarding the period of bearing a child - these are "embryo" and "fetus".

Conventionally, intrauterine development of the fetus is divided into two stages:

1. The first embryonic period lasts eight weeks. The embryo that develops in the uterus at this time is called an embryo.

2. The fetal stage begins from the ninth week and during this period of pregnancy the fetus is in the womb.

First week

The first thing that is necessary is to clearly understand what is the starting point. Speaking of obstetric terms: it is counted from the first day of the last menstruation. The embryonic term of pregnancy is the true term from the time of conception. On average, it is less than obstetric by 2 weeks.

Pregnancy starts from the moment of fertilization... The mature male cell (sperm) merges with the female. This process takes place, as a rule, in the ampullar section of the fallopian tube. The egg and sperm carry half of the chromosomes of the future human. The result of their fusion is the emergence of a new zygote organism. This organism has a full-fledged chromosome set that determines the sex of the child, eye color and even character.

A few hours later, the egg divides exponentially and descends into the uterine cavity through the fallopian tube. This process takes place within 5 days.

As a result of division, a multicellular, blackberry-like organism appears. At this stage the embryo is called morula... On the seventh day (approximately), the morula is implanted into the wall of the uterus. The blood vessels of the uterus connect with the villi of the outer cells of the embryo, and the placenta is subsequently formed. The organs and tissues of the fetus develop from the internal cells of the morula. The outer cells give rise to the development of the umbilical cord and membrane.

As for the signs and symptoms of pregnancy at this time, they are not felt.

Second-fourth week

In the second week of pregnancy, outdoor the cells of the embryo grow into the lining of the uterus, the formation of the placenta, neural tube and umbilical cord begins, subsequently from which the nervous system develops.

This is a difficult and important period. Important systems and organs begin to form in the baby. In the third week, the rudiments of the digestive, circulatory, respiratory, excretory and nervous systems appear. In place of the future head, a wide plate is formed, which will subsequently give rise to the brain in the brain. A child's heart begins to beat on the 21st day.

This week the development of the rudiments of the liver, intestines, lungs and kidneys begins... The heart works harder, pumping more and more blood through the circulatory system.

In the fetus, at the beginning of the fourth week, folds of the trunk and the rudiment of the spine appear. On day 25, the neural tube is fully formed.

At the end of the week, the spine forms, dividing the embryo into two halves with the upper and lower limbs, and the muscular system.

In the fourth week, eye pits form.

Fifth week

29-35 days of pregnancy is characterized by the onset the formation of the following systems and organs:

• circulatory system;
• digestive system, pancreas, liver;
• respiratory system: trachea, lungs, larynx;
• sense organs: inner ear and eyes;
• reproductive system. Precursors of germ cells are formed;
• nervous system. Parts of the brain begin to form;
• limbs continue to form, the rudiments of the legs appear;
• the nasal cavities and upper lip are formed on the face.

Sixth week

In the sixth week embryo length reaches about 5 mm.

1. The placenta begins to form. But between her and the embryo, blood circulation has not yet been formed.
2. The parts of the brain continue to form. At this stage of pregnancy, it is possible to record the signals of the fetal brain when performing an encephalogram.
3. The muscles of the face and eyes begin to form. They are already more pronounced. The eyelids are forming.
4. The heart completes division into chambers (atrium and ventricles).
5. The development of the ureters begins, primary kidneys appear.
6. Sections of the gastrointestinal tract begin to form.

Seventh week - completion time the formation of the umbilical cord and the establishment of uteroplacental circulation... Nutrition and respiration of the fetus is now carried out by the circulation of blood through the vessels of the umbilical cord and placenta.

During this period of pregnancy, the embryo is still bent in an arcuate manner. The size of the head is almost half the size of the embryo; there is a small tail on the pelvic part of the body.

By the end of the week, the length from the crown to the sacrum grows to 15 mm.

Upper limb development continues, the fingers are already clearly visible, but they are not yet separated from each other. The fetus begins to make spontaneous hand movements in response to stimuli.

Eyes at seven weeks are already well formed and covered with eyelids, protecting from drying out. On the sides of the head, two paired eminences are formed, the future ears. There is a nasal blockage. The parts of the brain are developing intensively.

Eighth week

At the eighth week, the body of the embryo begins to straighten. Important systems and organs continue to form:

• heart;
• digestive system;
• brain;
• hearing organs
• lungs;
• reproductive system;
• urinary system;

There is an intensive growth of the head and limbs: upper and lower. Ossification of the skull of the long bones of the arms and legs is noted. There is no longer a skin membrane between the fingers.

The child's face is already more familiar to humans. Eyes covered with eyelids are well expressed on it, there are auricles and a nose, the formation of sponges ends.

At the eighth week of pregnancy begins fetal period of fetal development.

Ninth week

The size of the fetus at the beginning of the ninth week is approximately 22 mm. By the end of this period -31 mm.

Placental vessels improve, placental - uterine blood flow improves.

The joints of the fingers and toes are formed. The fetus is actively moving, squeezing the fingers. The child's head is lowered, pressing the chin closely to the chest.

During the ninth week of pregnancy the cardiovascular system also changes... The heart of the child makes up to 150 beats per minute, pumping blood through the blood vessels. The composition of the fetal blood is completely different from the blood of an adult. It contains exclusively erythrocytes.

During this period, the organs of the endocrine system and the brain are actively developing, the structures of the cerebellum are being formed, the cartilaginous tissue is being improved, and the formation of the vocal cords is taking place.

By the end of the tenth week, the child begins to develop buttocks, the previously existing tail disappears. In the uterus, the fetus is in a semi-bent state in a free position.

In response to stimuli, the fetus already performs not chaotic, but reflex movements... The baby makes movements, feeling contact with the walls of the uterus. He turns the head, bends and unbends the arms and legs, pushes to the side. Since the size of the fetus is still very small, the woman does not feel these movements.

The development of the diaphragm ends, the sucking reflex is formed.

Eleventh week

The coccygeal-parietal size of the fetus by the end of this week increases to 5 cm. The body of the fetus is still disproportionate. The child has a large head, small torso, disproportionately long arms and short legs in all joints bent and pressed to the tummy.

The eyes continue to develop, the iris is formed, which in the future determines the color of the eyes.

The placenta during this period is already sufficiently developed and well performs its functions:

• removes waste products and carbon dioxide;
• provides oxygen and nutrients to the fetus.

The genitals develop according to the male or female type. The digestive system is being improved. The intestine is stretched in length, keeping it, like in an adult, in loops. Peristalsis begins, its periodic contraction. The child makes swallowing movements.

During the twelfth week, the baby's nervous system is being improved. And, despite the fact that the brain is still small, it exactly repeats the structure of the adult brain.

Reflex movements are improved... The fetus at this stage of development can squeeze the fingers into a fist, actively suck the thumb.

In the child's blood, leukocytes begin to be produced, and single respiratory movements appear. The fetus's lungs do not function before birth, but the baby imitates breathing by making rhythmic movements with the chest.

At the end of this week, the fetus has a clearly visible neck, eyebrows and eyelashes.

Thirteenth Fourteenth Week

At the thirteenth week of development, the size of the fetus is about 75 mm. Body proportions change. In relation to the body, the size of the head is no longer so large. The limbs are lengthened: both upper and lower.

The digestive and nervous systems continue to improve... The embryos of milk teeth appear under the lower and upper jaws.

The baby's face is already fully formed, the ears, eyes and nose are clearly visible.

By the end of the fourteenth week, the size of the fetus is already 8-9 cm. The proportions of the body are more familiar. A chin and cheeks appear on the face, a nose and forehead are well defined. The surface of the fetus's body is covered with hairs that perform a protective function and retain the lubricant of the skin.

The bones of the fetus are strengthened, motor activity is enhanced. The child bends, turns over, makes swimming movements.

The development of the ureters, bladder and kidneys ends. The endocrine system is being improved. The cells of the pancreas begin to produce pituitary cells and insulin.

Genital organs change... In girls, the ovaries "leave" in the pelvic cavity, in boys, the prostate gland begins to form.

Fifteenth sixteenth week

In the fourth month of pregnancy, the weight of the fetus is 75 grams, the size is 10 cm. The blood vessels grow in length, their walls are strengthened.

In connection with the ingestion of amniotic fluid, original feces begin to be produced.

By the end of the sixteenth week, the fetus already has all the systems and organs. The kidneys work actively, and small amounts of urine are excreted into the amniotic fluid every hour.

The baby has very thin skin at this stage of development.... Through it, the blood vessels are visible, there is practically no fatty tissue. The child's skin is bright red, covered with grease and vellus hairs.

On the face, the cilia and eyebrows are well pronounced. Marigolds are formed on the toes, covering the edge of the nail phalanx.

The child begins to make grimaces, facial muscles are formed. During this period, there is a semblance of a smile and a frown.

Seventeenth week

Fruit size 14-15 cm, weight - about 150 g.

Under the still rather thin skin, fatty subcutaneous tissue begins to develop. Milk teeth, while continuing to develop, are covered with dentin. Embryos of permanent teeth appear.

The child begins to respond to sound stimuli, actively moves when strong and harsh sounds appear.

The fetus changes its position. His head is raised, the arms are bent at the elbows, the fingers are clenched into fists all the time. The fetal heartbeat is felt more clearly.

Eighteenth - nineteenth week

A mode of wakefulness and sleep is formed. The child sleeps most of the time.

A woman at this time can already feel the movement of the child as gentle jolts. The baby's movements become more active when the woman is excited, which is reflected in the emotional state of the baby.

At the nineteenth week, movements become more noticeable and frequent. They can already be felt not only by the mother, but also by other people, putting their hands on their stomachs.

The endocrine system of the child is being improved... The pituitary gland, the adrenal glands, the thyroid and pancreas, and the sex glands function quite actively.

The composition of the blood has changed completely. In the blood, in addition to leukocytes and erythrocytes, there are lymphocytes and monocytes. The spleen begins to participate in hematopoiesis.

Twentieth week

The body length of the fetus increases to 25 cm, the weight reaches 340 grams.

There is an intensive development of subcutaneous adipose tissue... At the twelfth week, coordination of movement improves, a blink reflex appears. The fetus can close its eyes, facial expressions are pronounced.

The child's activity changes during the day. He reacts with violent stirring to a stuffy room and to loud sounds.

Twenty-first to twenty-third weeks

Changes at this stage are characterized by:

At the twenty-third week, the body weight of the fetus is -500 g, the body length is about 30 cm. Pigment is synthesized in the skin, which affects the acquisition of a bright red color by the skin. Fatty subcutaneous tissue is still thin. The baby looks wrinkled and thin. All skin is covered with lubricant, which is more abundant in the folds of the body: axillary, elbow, inguinal.

The genitals continue to develop: in girls, the ovaries, in boys, the scrotum.

The child's breathing rate increases up to 50-60 times per minute.

At this stage of development a swallowing reflex appears... The baby constantly swallows amniotic fluid, which contains particles of skin lubricant. Swallowing water causes hiccups in the child, which a woman can feel in the form of rhythmic movements.

Twenty-fourth week

The movements of the child are becoming clearer and clearer. Its body length is 30-32 cm, its weight increases to 600 grams by the end of the week. The fetus takes up almost all the space in the uterus, but it can roll over and change position. Muscles grow vigorously.

At the end of the sixth month, the child's senses are well developed. Eyesight is already functioning and when a bright light hits a woman's belly, the baby closes his eyelids.

The fetus, thanks to its well-developed hearing, already distinguishes sounds and accordingly reacts to them.

An emotional connection develops between the child and the mother. If the mother experiences negative emotions (melancholy, fear, anxiety), the baby experiences the same feelings.

Twenty-fifth - twenty-sixth week

At the twenty-fifth week, the skin becomes elastic, the number of folds and their severity are reduced due to the fatty subcutaneous tissue.

Passes intensive bone marrow development, which takes the main role in hematopoiesis. Bones continue to strengthen.

At this time, alveoli are formed - elements of lung tissue that, before the birth of a child, resemble deflated balls without air. They will straighten out after the first cry of the baby.

Muscle tissue continues to grow. The length of the fetus is 35 cm, weight -760g. The child develops a sense of smell.

The genitals continue to form.

Twenty-seventh - twenty-eighth week

The baby in the womb is quite active... He has a well-functioning thyroid, pancreas, pituitary gland, and an individual metabolism.

The fetus becomes viable by this age. Subcutaneous fatty tissue accumulates. The skin is still bright red, vellus hair gradually begins to fall out, remaining on the shoulders and back.

Eyebrows, eyelashes and scalp hair become darker. The child opens his eyes more often. The cartilage of the ears and nose is still soft.

During this period, more actively one of the two hemispheres of the brain functions, which influences who the child will be in the future: left-handed or right-handed.

Twenty-ninth - thirty-second week

The fruit has grown enough. It occupies almost all the space in the uterus, located in a certain position: downward with the head or buttocks. The movements are felt as periodic tremors of the arms and legs.

The load on the cardiovascular system increases. The lungs are prepared for the birth of a child, a surfactant is produced. The area of ​​the cortex and the number of convolutions in the brain increase.

Baby the mode of wakefulness and sleep changes... However, he still sleeps more time, actively moving during wakefulness, which is well felt by the mother.

The baby's eyes are already fully formed. They are closed during sleep and open during wakefulness. The fetus reacts to light by dilating and constricting the pupils. The color of the iris of the eyes is blue (the same for all children). After birth, he changes.

The size of the brain increases. At this stage, it accounts for 25% of the brain volume of adults.

At the end of the thirty-second week, the growth of the fetus is 43-44 cm, weight is about 2000 grams. The child in the uterine cavity is becoming more and more cramped. He moves less and less. The position of the fetus is fixed. At this time, there is little likelihood that the child will roll over.

The skin becomes smoother and brighter, the layer of adipose tissue increases... The layer of protective lubricant increases, and the vellus hair is wiped off more and more.

The mass of the heart increases, the formation of the alveoli is almost complete, the tone of the blood vessels increases, the brain is already fully formed.

Thirty-fourth - thirty-eighth week

At the thirty-fourth week, the bones of the baby's skull are soft and mobile, thanks to the presence of fontanelles, which will close some time after childbirth.

Hair grows actively on the head, taking on a certain color, which will also change after childbirth.

Bones are intensively strengthened and the fetus begins to take calcium from the mother's body. A pregnant woman may have seizures at this time.

Every day the child adds 25-35 grams... During this period, the weight can vary greatly. All internal organs of the child continue to improve.

The child becomes more plump. The fat layer is already well developed, the skin color is lighter, and the lungs are fully formed. The cartilages of the nose and auricles are more elastic and dense.

The maturation of the digestive system is over. Contractions occur in the intestines and stomach, which promote the push of food.

The height and weight of a child varies greatly. The fetus is already completely ready for birth.

Thirty-ninth - fortieth week

14 days before giving birth, the baby begins to descend and press against the pelvic bones. The placenta is gradually aging, metabolic processes deteriorate.

In the fortieth week the uterus begins to contract... The pregnant woman has sensations aching pain lower abdomen. The fetal head is more closely attached to the pelvic cavity, the neck opens slightly.

Due to the softness and pliability of the bones of the skull, the baby's head changes shape and easily passes through the birth canal.