How is the intrauterine development of the child?

, medical expert
Last reviewed: 23.04.2024

All iLive content is medically reviewed or fact checked to ensure as much factual accuracy as possible.

We have strict sourcing guidelines and only link to reputable media sites, academic research institutions and, whenever possible, medically peer reviewed studies. Note that the numbers in parentheses ([1], [2], etc.) are clickable links to these studies.

If you feel that any of our content is inaccurate, out-of-date, or otherwise questionable, please select it and press Ctrl + Enter.

First week of intrauterine development of the child

The fertilized egg, or rather - already the egg, moves through the uterine tube into the uterus. The egg is the egg that has merged with the sperm. It contains all the information about the future child - gender, eye color and possible talents! From the moment of conception, it is a person who has never been before. (If, of course, one does not believe in reincarnation and the transmigration of souls, by the way, even if we believe, the physical shell will still be different.) On the 3-4th day, the egg enters the uterus, and from the 5th to the 9th day after fertilization, the egg is implanted into the endometrium - the layer of the uterus lining it from the inside. Here she begins to "sprout" (implant) (if you draw an analogy with plants - lets the roots in) and gets food from a future mother.

trusted-source[1], [2], [3], [4]

The second week of intrauterine development of the child

Implantation is completed by the twelfth day. This is the real beginning of pregnancy. The egg begins its growth, which occurs by division. First, two cells are formed from one cell, then a transverse constriction appears, dividing these two cells into two more - there are four of them, then eight, sixteen, thirty-two, and so on. At the same time, two sheets - outer and inner - begin to form, by "screwing" one layer of cells into another. The diameter of the egg is about 1 mm.

The third week of intrauterine development of the child

This week is the most responsible for the embryo. During this period, all the unfavorable factors - alcohol, drugs, smoking, taking medicines, infections, can inflict irreparable harm on the fetus. In the third week the future placenta, future blood vessels, sex cells form, respiratory, digestive and nervous systems, skeleton, muscles, and skin begin to form.

Fourth week. The embryo, which before was similar to a disk consisting of three layers, gradually turns into a cylinder. Individual organs are beginning to form. And the heart appears first. Its reduction can be recorded from the 23rd day of pregnancy. Begin to appear oral and anal fossa, the primary intestine, similar to the tube, liver, pancreas, spleen. By the end of the first month, the length of the embryo is about 5 mm, and it looks like a bean with small outgrowths, which later become handles and legs.

The fifth - the sixth week

This period is very responsible for the fact that if the embryo is affected by adverse factors, it may develop developmental defects of the central nervous system.

At this time, the embryo resembles the letter "E". The head is quite clearly visible, the tummy is sticking out in the middle, rudimentary arms and legs are visible, and a ponytail is seen from below. The pens grow faster than the legs. At this time, there is a laying of the nervous tissue. On the head there are olfactory fossa - the future nostrils. The development of the bronchial tree begins.

The membrane separating the anal fossa from the cavity of the primary intestine breaks through and the gut becomes open on both sides. The heart, with a volume of a small cone, consists of four chambers (two atria and two ventricles) separated by valves and separated from them by vessels. Formation of visual vesicles - future eyes. In this period, one can already discern the rudimentary ears on the sides of the head. The total length of the embryo is about 2.5 cm.

Seventh - eighth week

The trunk is formed and lengthened, reaching a length of about 3 cm. Shoulders begin to form, and later the limb is divided into the shoulder, forearm and the wrist. Gradually, muscles and nerves form. Appearance of the germinal glands. The diaphragm separates the thoracic cavity from the abdominal cavity.

There are changes on the face: there are two small cracks - eyes, two grooves - ears. A small nose with nostrils is visible, and the mouth is bordered by sponges (if the three processes of the lips do not converge, a "hare lip" is formed).

At the eighth week, the embryonic period ends - the embryo becomes the fruit.

In the eighth week the fetus can already feel pain. Moreover, receptors (sensitive cells) of the fetus are more sensitive than in newborns or adults.

In this period, the movements of the fetus are already visible on the ultrasound.

Usually during this period (with unwanted pregnancy) gynecologists make an abortion. German operators, together with doctors, filmed a film about how the process of such a murder is going on. Fruit wrings pens and legs from the curette of a gynecologist (the instrument that is being aborted), hides, in general, tries in every possible way to escape, but ...

Think before you have an abortion! Think about how to avoid unwanted pregnancy!

At the end of this period, the fruit length is about 3 cm, weight is about 3 g.

The ninth - the tenth week

The face of the fruit begins to acquire "human" features - the eyes from the sides of the head "converge" to the center of the face. They are still closed, but the iris already has a pigment.

During this period, the growth of the trunk is accelerated, and the growth of the head slows down.

The liver and kidneys are already almost developed, and the kidneys begin to form urine, which is poured into the amniotic fluid.

Fruit loses its "tail". He can already suck his fingers, touch his hands, the umbilical cord, push off from the walls of the uterus and swim in amniotic fluid.

Begins begin to form rudiments of the teeth, the intestine is entirely in the abdominal cavity.

The length is about 4 cm, and the weight is 5 g.

The eleventh - the twelfth week

All organs and systems begin to function: the liver secretes bile, the villi are formed on the intestinal mucosa, which in the future will absorb nutrients, the intestine begins to peristaltic (shrink), while continuing its rotation in the abdominal cavity so that it takes its usual position. The fruit begins to swallow the amniotic fluid that contains the hairs, the deceased skin cells, which, digesting, form the original calmetonium.

During this period, marigolds begin to appear on the fingers and toes and it is already possible to determine the sex of the unborn child.

The body length is about 6 cm, and the weight is about 10 g.

Thirteenth to fourteenth weeks

At the 13th week, the fetus is almost completely formed taste buds, and it begins to actively swallow the amniotic fluid, preferring sweet amniotic fluid waters of a different taste. Yes, at such an early age he is already a gourmet! After all, he does not need to drink them at all, since he receives all necessary nutrients from his mother through the placenta, which, by the way, is fully formed by the 13th week. Most likely, swallowing amniotic fluid and sucking a finger, the fetus prepares for extrauterine nutrition.

During this period, he has phases of sleep and wakefulness. Becomes cute face, there are cheeks. The fetus becomes very mobile, however, compared to earlier periods, its movements are more smooth. On the body appear hairs and sweat glands.

The fruit length is about 10 cm, and the weight is about 25 g.

Fifteenth - the sixteenth week of intrauterine development of the child

Hair begins to grow on the head, handles bend in the joints, and touch develops. The fetus continues to grow, but new organs no longer appear, since they are already formed. He can frown, smile, blink his eyes in response to irritation.

Weight is already about 80 grams, and height - 110-115 mm.


Seventeenth to eighteenth weeks

The skin is no longer so thin, but still transparent, red, it can clearly see the first hair - lanugo. The eyebrows begin to appear. Girls have a fully formed uterus and ovaries. Muscles become stronger, and movements are more active, and experienced (re-born) women can already feel them.

The height is about 13 cm, and the weight is about 150 g.

The nineteenth - the twentieth week

The boys are clearly visible male genitalia. The ossification of the auditory ossicles is almost completed and the fruit begins to hear external sounds: the heartbeat of the mother, her voice, the voices of other family members.

The volume of the brain increases rapidly. Starting from the 20th week, it increases every month by 90 g. Fruit begins to blink more often. The legs finally reach the final proportions, and he begins to push them more and more. A woman can already feel the movement of her baby in the stomach. The length of the fetus is about 15 cm, and the mass is 260 g.

Twenty-first - twenty-second weeks

The skin becomes less red, but it is wrinkled and through it the vessels and internal organs are visible. More hair appears on the head. At the fingertips appeared a characteristic, inherent only imprint.

They say that the taste of the amniotic fluid swallowed by the fruit can form the child's subsequent nutritional preferences. In addition, since the fruid already hears, he gets used to the voice of the mother, father and other domestic people. And if the family reigns in peace, love and respect, then the newborn child will also be calm; If there are constant scandals in the family, then the child will be nervous and restless. It is also noted that if a mother reads a book during pregnancy, she may later become a favorite book of the child.

From the 18th to 19th week, start talking to your future child, create a positive emotional background! Thanks to this, you will have harmonious, friendly relations with the child before his birth and this will facilitate his adaptation to the extrauterine life after birth.

The length of the fruit by the end of the 23rd week is about 20 cm, and the mass is 450 g.

Twenty fourth - twenty fifth week

The fetus sleeps less and sleeps during the day for a rather long time. And since he does not sleep, his movements become more active: he commits from 20 to 60 movements in 30 minutes. The fetus reacts to sounds penetrating to it from the outside. He has a rather complex facial expression, often sucks a finger, sometimes hiccups. However, the space for traffic remains less and less.

If you want your child to be musical, starting from the 24th week of pregnancy, often include music. But remember that the fetuses prefer classical music, and rap, rock and other "rhythmics" leads them into a nervous state.

Growth of the fetus by the end of the 25th week is about 22 cm, and weight - 700 g.

The twenty-sixth to the twenty-seventh weeks

The fetus begins to feel the light, and if the light is too bright, it can even turn his head away. Naturally, he sees light when he opens his eyes. According to special studies, the electrical activity of his brain corresponds to that of a full-term newborn. But the most important thing happens in his lungs. There begins to produce a special substance - surfak-tant, which prevents the recession of the lungs. Without this substance, the child can not breathe air. And although by this time the fetus has passed only 2/3 of the way of its development, it is almost ready to be born, and if this happens, it can survive. Especially favorable prognosis for survival in girls.

Fetal growth is about 25 cm, and weight - about 1 kg.

The twenty-eighth - twenty-ninth week

The fetus makes respiratory movements, but since it is in the amniotic fluid, it is naturally only the lungs that enter the lungs.

You can be scared for your future child: "After all, he can drown like this!". No! He will not drown. First, amniotic fluid has the same composition of salts, glucose and other substances as the fetal blood. So they can not hurt. Secondly, the blood vessels carrying blood to the lungs and from them, still practically do not function. They will earn only when the child is born. Third, the fetus receives oxygen through the umbilical cord and the placenta from the mother.

During this period, he opens his eyes completely (naturally, when he does not sleep) and can already translate his sight from the object to the object (although, apart from blood vessels, there are nothing to consider the umbilical cord and bright outbreaks from outside).

He already hears well and, with loud, sharp sounds, is frightened and even bounces, and with the calm voice of his mother or father, smooth, quiet music - calms down.

Its dimensions are about 37 cm, and the mass is about 1.4 kg.

Thirtieth - thirty first week

The fetus is already so large that it becomes cramped in the uterus and therefore it starts to move less, taking its characteristic collective posture: the head is tilted down and pressed against the chest by the chin, the pens are folded on the chest, the legs are bent at the knees, tucked to the tummy and crossed. In this position, it occupies the least place.

His eyes have a gray-blue color, the pupils react to light (they expand in the dark and narrow in the light).

The fingernails are already fully formed on the toes of the feet.

Its height is about 40 cm, and its mass is about 1.7 kg.

Thirty-second - thirty-third week

During this period, the fetus usually takes the position in which it will be born - the head down. But sometimes he does not have time to turn around and occupy the wrong position - gluteal or transverse, and then during labor there can be difficulties, which can be solved by surgery - cesarean section.

The skin begins to acquire a normal, pink color, it is not so wrinkled due to the accumulation of fat in the subcutaneous fat.

During this period, the fetus has all the reflexes inherent in newborns. But they are much weaker, and the muscle tone is not as pronounced as in newborns.

The growth is usually about 43 cm, and the mass is about 2 kg.

Thirty-fourth - thirty-fifth week

The placenta is already reaching a large size - after all, the fetus needs a strong diet.

The hair on the skin (lanugo) almost disappears, and the skin itself is gradually covered with a germinal lubricant.

The head (if the child is positioned correctly) begins to sink to the entrance to the pelvis, and as the fetal space remains less and less, it sometimes makes sharp and prolonged movements with legs, trying to "straighten". And then you feel good how he "tramples" on your liver.

Its growth is about 45 cm, and the mass is about 2.4 kg.

Thirty-sixth to thirty-seventh weeks

The skin of the baby becomes very smooth, it is still covered with original grease, but partially this grease starts to separate and float in the amniotic fluid. Due to sufficiently developed subcutaneous fat, the body temperature of the baby is kept at a higher level than the mother's body temperature. In the intestine, a lot of meconium has already accumulated, since the fruit actively swallowed the amniotic fluid.

During this period, ossification continues, and long tubular bones (thigh, shoulder, shin) are almost the same as those of the newborn.

The height is about 48 cm, and the mass is about 2.8 kg.

During this period, if there is such a need, it is already possible to do a cesarean section. The extracted child, as a rule, is fully viable, and all the organs and systems of his body can function as if he were born on his own on time.

And why do you need to do cesarean in such a time? First, if the mother develops the phenomenon of late gestosis (pre-eclampsia): blood pressure rises, swelling on the legs and lower abdomen increases, a protein appears in the urine. Secondly, if an operation had already been performed by cesarean section, and from that moment less than three years have passed. In this case, during labor, there may be a risk of rupture of the uterus along the old scar. Thirdly, if the mother suffers from diabetes, heart disease or other serious illnesses, there is no point in waiting for natural births to begin that could worsen the condition of both the mother and the child. Fourth, if the pelvic dimensions do not allow the child to pass unhindered through the natural birth canal.

In general, the testimony to the caesarean section is determined by the gynecologist, and, as a rule, not himself, but a medical consultation is being held, which solves the question of this or that method of delivery.

Thirty-eighth - thirty-ninth week

The future child continues to grow and gain strength. He already can not practically move - it's so tight in his uterus. The bones of the skull are not yet fused together and form two fontanel - large and small. Due to this feature, while passing through the mother's birth canal, the child's head will be configured. That is, skull bones can "creep" one on top of another, reducing the size of the head, so that it can be born without hindrance.

At the end of this period, the fetus weighs about 3 kg, and its height is about 50 cm.

Fortieth week of intrauterine development of the child

The fruit is already fully ready for birth and even wants it. He only waits for the moment when the mother's body will accumulate a sufficient number of hormones that provide the beginning of labor.

The skeleton of the baby consists of 300 separate bones, since not all the bones have ossified and coalesced with each other (for example, the skull bones consist of six separate bones, whereas the adult skull is a single whole). The number of bones in an adult is almost one hundred less.

50% of his body weight is fat. The height is about 50 cm, and the mass is about 3.5 kg.

You are reporting a typo in the following text:
Simply click the "Send typo report" button to complete the report. You can also include a comment.