At what week of pregnancy is the sex of the baby determined. How long does it take for a child’s sex to be determined, and what factors does it depend on? How does the fetus develop at this stage of pregnancy?

Boy or girl? This is perhaps one of the most pressing questions during pregnancy, which the expectant mother not only asks herself, but also hears in unlimited quantities from relatives, friends and acquaintances. Despite the fact that the situation can no longer be influenced in any way, conversations on this topic constantly continue and innumerable arguments are given about who is better. Finding out the sex of the child using a variety of methods - analyzing the shape of the abdomen, the degree of maternal beauty (which the girl should take), the timing of toxicosis, and the like folk signs, unfortunately, not confirmed by medicine, is up to a certain time the main intrigue of pregnancy. When and how can this secret be revealed?

When is the gender of a child determined?

Fertilization occurs as a result of the union of two cells - a male cell, or sperm, and a female egg. Both cell nuclei fuse and become the fertilized egg. Each of the cells that form the egg carries the characteristics of one of the parents. The carriers of these characteristics are chromosomes. The nucleus of every cell human body contains 46 chromosomes: 23 from the father and 23 from the mother. The chromosomes of the mother and father form a pair. Each person in any cell of the body has 23 pairs of chromosomes that are unique to him and determine his individual characteristics - traits of appearance, intelligence or character.

The sex of the child is the result of a random selection of chromosomes. Let's first pay attention to appearance Chromosomes: Their size and shape vary, but every normal cell has at least 44 chromosomes, each of which has one similar to itself. Grouped in twos, they form 22 pairs. They are classified by size: the largest pair has number 1, and the smallest - number 22. The 23rd pair stands apart: in a woman, it, like all the others, is formed by two similar chromosomes, designated by the letter X. And in a man, 23- The th pair contains only one X chromosome along with a smaller one, designated by the letter Y.

In the body of the parents, the egg or sperm are cells containing only half of the chromosomes, that is, 23 each. Thus, all eggs are of the same type: they all have an X chromosome. Spermatozoa are of two types: some of them have an X chromosome in the 23rd pair, others have a Y chromosome. If an egg by chance unites with a sperm carrying an X chromosome, the egg will develop into a girl; and if chance leads to fertilization of the egg by a sperm containing a Y chromosome, then the egg develops into a boy. Thus, sex determination occurs already during fertilization.

Theoretically, it would be possible to find out the sex of the child from this moment, if doctors had at their disposal technical means that would allow them to observe the egg without the risk of damaging it. Perhaps the day will come when chance will give way to science and parents will choose the sex of their unborn child themselves; in any case, this will happen only if the X- and Y-spermatozoa are separated in the sperm.

As soon as the egg is formed, it begins to divide into 2, 4, 8, 16, etc. cells. After several days, the cells functionally specialize: some for the formation of sensory organs, others for the intestines, others for the genital organs, etc. It is the Y chromosome that tells the sex cells that they will develop according to the male type. External signs the sexes become noticeable by the beginning of the 4th month of pregnancy. But at the chromosomal level, which also determines its external manifestations, sex exists from the moment of fertilization. That is why, in some cases, it is possible to find out the sex of the child already at the beginning of pregnancy (2-3 months) thanks to chromosomal studies of embryonic cells. To do this, a so-called puncture is performed - taking placenta cells, amniotic fluid or fetal blood for analysis; It should be noted that this procedure is unsafe for maintaining pregnancy and can lead to the threat of termination. Therefore, it is carried out according to strict indications - often to exclude genetic pathology. A little later and with a lesser degree of certainty, the sex of the baby can be determined thanks to echography - a kind of radar that, using ultrasound, allows you to see the small penis or labia of the fetus in the mother's uterus.

When can you find out the gender of your baby?

So, how and when can you find out the gender of a child in the womb? First of all, this allows us to do analysis chorionic villi. Its essence lies in the fact that the doctor, either through the entrance to the uterus or using a needle inserted through the abdominal wall, takes a tiny piece of tissue from which the placenta will develop. By examining this tissue, he can determine the sex of the child, as well as obtain information about genetic defects and chromosomal abnormalities, which allows him to make a timely decision to terminate the pregnancy. The advantage of this method is that parents receive the answer to their question about the sex of the future baby in the earliest stages of pregnancy - at 8-10 weeks. But the disadvantage and danger is that such a study can cause the threat of miscarriage. Therefore, it is performed infrequently and only for medical reasons.

A safer and more commonly used method is ultrasound examination. For this purpose, the skin of the abdomen expectant mother lubricate it with a special gel and move the sensor over it. The sensor emits and collects reflected ultrasonic waves, which are converted into an image on the screen. This procedure takes 15-20 minutes and allows you to see the position of the fetus and placenta, clarify the gestational age, ensure the correct development of the fetus and, if the gestational age is long enough, try to find out the sex of the child. The only disadvantage of this method is that information about the sex of the child in most cases can be obtained after the 20th week of pregnancy, and even then the percentage of diagnostic errors remains high. In addition, the child may turn around so that it is not possible to see his genitals. With good resolution of the ultrasound machine, the sex of the child can be determined at earlier stages of pregnancy - after approximately 12 weeks, but research in the second trimester of pregnancy is more reliable; It is at this time that most couples find out the expected sex of the fetus. Although some parents remain in the dark about the sex of the child until birth - either voluntarily or involuntarily, when ultrasound cannot definitively answer this question.

Technical capabilities of ultrasound

It is now possible to find out the sex of a child, if his position allows it, using the most modern advances medical equipment. The operating principle of ultrasound is based on the reflection of an ultrasonic wave from the tissues of the body, the device capturing the reflected signal and obtaining on the screen a planar image of the organs through which the ultrasound passed - this is how two-dimensional ultrasound works.

Later, thanks to new computer technologies, a scanner with the possibility of three-dimensional reconstruction in real time appeared, and the intensity of the ultrasound wave remains the same, but there are much more diagnostic possibilities thanks to the three-dimensional volumetric image of the fetus. Three-dimensional ultrasound data provide additional information that is very important for diagnosing fetal malformations - limbs, spine, face.

Parents can receive a black and white printout of a two-dimensional ultrasound image as a souvenir; more modern devices allow you to receive a recording of ultrasound data in the form digital photo, as well as on a VHS cassette, CD or DVD, giving a three-dimensional image in motion. Therefore, for parents who want to start a children's album from the stage of the child's intrauterine life, it makes sense to inquire in advance what kind of equipment is equipped at the clinic or antenatal clinic where the research is supposed to be done.

Of course, any parents are interested in learning as soon as possible the secret that nature has hidden from them for the time being. But don’t forget that, by and large, it doesn’t matter who is born to you - a boy or a girl. After all, even if your guesses regarding the baby’s gender do not come true, you will still love him.

Pregnancy is a physiological process in which a new organism develops in the uterus, resulting from fertilization. Pregnancy lasts on average 40 weeks (10 obstetric months).

In the intrauterine development of a child, two periods are distinguished:

1. Embryonic(up to 8 weeks of pregnancy inclusive). At this time, the embryo is called an embryo and acquires characteristic human features;
2. Fetal(from 9 weeks until birth). At this time, the embryo is called a fetus.

The growth of a child, the formation of its organs and systems occurs naturally during various periods of intrauterine development, which is subject to the genetic code embedded in the germ cells and fixed in the process of human evolution.

Embryo development in the first obstetric month (1-4 weeks)

First week (days 1-7)

Pregnancy begins from the moment fertilization- fusion of a mature male cell (sperm) and a female egg. This process usually occurs in the ampullary section of the fallopian tube. After a few hours, the fertilized egg begins to divide exponentially and descends through the fallopian tube into the uterine cavity (this journey takes up to five days).

As a result of division turns out to be a multicellular organism, which is similar to a blackberry (in Latin “morus”), which is why the embryo at this stage is called Morula. Approximately on the 7th day, the morula penetrates the uterine wall (implantation). The villi of the outer cells of the embryo connect with the blood vessels of the uterus, and subsequently the placenta is formed from them. Other outer morula cells give rise to the development of the umbilical cord and membranes. From internal cells After some time, various tissues and organs of the fetus will develop.

Information At the time of implantation, a woman may have small bloody issues from the genital tract. Such discharge is physiological and does not require treatment.

Second week (8-14 days)

The outer morula cells grow tightly into the lining of the uterus. In the embryo the formation of the umbilical cord and placenta begins, and neural tube, from which it subsequently develops nervous system fetus

Third week (15-21 days)

The third week of pregnancy is difficult and important period . At that time important organs and systems begin to form fetus: the rudiments of the respiratory, digestive, circulatory, nervous and excretory systems appear. At the site where the fetal head will soon appear, a wide plate is formed, which will give rise to the brain. On day 21, the baby's heart begins to beat.

Fourth week (22-28 days)

this week laying of fetal organs continues. The rudiments of the intestines, liver, kidneys and lungs are already present. The heart begins to work more intensely and pumps more and more blood through the circulatory system.

From the beginning of the fourth week in the embryo body folds appear, and appears vertebral primordium(chord).

Completed by day 25 neural tube formation.

By the end of the week (approximately 27-28 days) are being formed muscular system, spine, which divides the embryo into two symmetrical halves, both the upper and lower limbs.

During this period it begins formation of pits on the head, which will later become the eyes of the fetus.

Development of the embryo in the second obstetric month (5-8 weeks)

Fifth week (29-35 days)

During this period the embryo weighs about 0.4 grams, length 1.5-2.5 mm.

The formation of the following organs and systems begins:

1. Digestive system: liver and pancreas;
2. Respiratory system: larynx, trachea, lungs;
3. Circulatory system;
4. Reproductive system: precursors of germ cells are formed;
5. Sense organs: the formation of the eyes and inner ear continues;
6. Nervous system: the formation of parts of the brain begins.

At that time a faint umbilical cord appears. The formation of limbs continues, the first rudiments of nails appear.

On the face the upper lip and nasal cavities are formed.

Sixth week (36-42 days)

Length embryo during this period is about 4-5 mm.

Starts in the sixth week formation of the placenta. At this stage, it is just beginning to function; blood circulation between it and the embryo has not yet been formed.

Ongoing formation brain and its departments. At the sixth week, when performing an encephalogram, it is already possible to record signals from the fetal brain.

Begins formation of facial muscles. The fetal eyes are already more pronounced and uncovered by eyelids that are just beginning to form.

During this period they begin upper limbs change: they lengthen and the rudiments of hands and fingers appear. The lower limbs still remain in their infancy.

Changes in important organs occur:

1. Heart. The division into chambers is completed: ventricles and atria;
2. Urinary system. Primary kidneys have formed, the development of the ureters begins;
3. Digestive system. The formation of sections of the gastrointestinal tract begins: the stomach, small and large intestines. The liver and pancreas had practically completed their development by this period;

Seventh week (43-49 days)

The seventh week is significant in that it is finally The formation of the umbilical cord is completed and uteroplacental circulation is established. Now the breathing and nutrition of the fetus will be carried out due to blood circulation through the vessels of the umbilical cord and placenta.

The embryo is still bent in an arched manner; there is a small tail on the pelvic part of the body. The size of the head is at least half of the embryo. The length from the crown to the sacrum increases by the end of the week up to 13-15 mm.

Ongoing upper limb development. The fingers are visible quite clearly, but their separation from each other has not yet occurred. The child begins to perform spontaneous movements with his hands in response to stimuli.

Fine eyes are formed, already covered with eyelids, which protect them from drying out. The child can open his mouth.

The formation of the nasal fold and nose occurs, two paired elevations are formed on the sides of the head, from which they will begin to develop ears.

Intensive continues development of the brain and its parts.

Eighth week (50-56 days)

The body of the embryo begins to straighten, length from the crown to the coccyx is 15 mm at the beginning of the week and 20-21 mm on day 56.

Ongoing formation of important organs and systems: digestive system, heart, lungs, brain, urinary system, reproductive system(boys develop testicles). The hearing organs are developing.

By the end of the eighth week the child's face becomes familiar to the person: the eyes are well defined, covered with eyelids, the nose, the ears, the formation of the lips is ending.

Intensive growth of the head, upper and lower horses is noted In particular, ossification of the long bones of the arms and legs and the skull develops. The fingers are clearly visible; there is no skin membrane between them.

Additionally At eight weeks the embryonic period of development ends and the fetal period begins. From this time on, the embryo is called a fetus.

Fetal development in the third obstetric month (9-12 weeks)

Ninth week (57-63 days)

At the beginning of the ninth week coccygeal-parietal size fetus is about 22 mm, by the end of the week - 31 mm.

Happening improvement of blood vessels of the placenta, which improves uteroplacental blood flow.

The development of the musculoskeletal system continues. The process of ossification begins, the joints of the toes and hands are formed. The fetus begins to make active movements and can clench its fingers. The head is lowered, the chin is pressed tightly to the chest.

Changes occur in the cardiovascular system. The heart beats up to 150 times per minute and pumps blood through its blood vessels. The composition of blood is still very different from the blood of an adult: it consists only of red blood cells.

Ongoing further growth and development of the brain, cerebellar structures are formed.

Organs are developing intensively endocrine system , in particular, the adrenal glands, which produce important hormones.

Improves cartilage tissue: auricles, laryngeal cartilages, vocal cords are being formed.

Tenth week (64-70 days)

By the end of the tenth week fruit length from the coccyx to the crown is 35-40 mm.

Buttocks begin to develop, the previously existing tail disappears. The fetus is in the uterus in a fairly free position in a semi-bent state.

Nervous system development continues. Now the fetus performs not only chaotic movements, but also reflex ones in response to a stimulus. When accidentally touching the walls of the uterus, the child makes movements in response: turns his head, bends or straightens his arms and legs, and pushes to the side. The size of the fetus is still very small, and the woman cannot yet feel these movements.

The sucking reflex is formed, the child begins reflex movements with his lips.

The development of the diaphragm is completed, which will take an active part in breathing.

Eleventh week (71-77 days)

By the end of this week coccygeal-parietal size the fetus increases to 4-5 cm.

The fetal body remains disproportionate: small body, large head, long arms and short legs, bent at all joints and pressed to the stomach.

The placenta has already reached sufficient development and copes with its functions: ensures the supply of oxygen to the fetus and nutrients and removes carbon dioxide and metabolic products.

Further formation of the fetal eyes occurs: At this time, the iris develops, which will later determine the color of the eyes. The eyes are well developed, half-closed or wide open.

Twelfth week (78-84 days)

Coccygeal-parietal size fetus is 50-60 mm.

Goes clearly development of the genital organs according to the female or male type.

Happening further improvement digestive system. The intestines are elongated and arranged in loops, like those of an adult. Its periodic contractions begin - peristalsis. The fetus begins to make swallowing movements, swallowing amniotic fluid.

The development and improvement of the fetal nervous system continues. The brain is small in size, but exactly replicates all the structures of the adult brain. The cerebral hemispheres and other sections are well developed. Reflex movements are improved: the fetus can clench and unclench its fingers into a fist, grabs thumb and actively sucks it.

In fetal blood Not only red blood cells are already present, but the production of white blood cells - leukocytes - also begins.

At this time the child single respiratory movements begin to be recorded. Before birth, the fetus cannot breathe, its lungs do not function, but it makes rhythmic movements of the chest, imitating breathing.

By the end of the week the fetus eyebrows and eyelashes appear, the neck is clearly visible.

Fetal development in the fourth obstetric month (13-16 weeks)

Week 13 (85-91 days)

Coccygeal-parietal size by the end of the week is 70-75 mm. The proportions of the body begin to change: the upper and lower limbs and torso lengthen, the size of the head is no longer so large in relation to the body.

Improvement of the digestive and nervous systems continues. The embryos of baby teeth begin to appear under the upper and lower jaws.

The face is fully formed, the ears, nose and eyes are clearly visible (the eyelids are completely closed).

Week 14 (92-98 days)

Coccygeal-parietal size by the end of the fourteenth week it increases up to 8-9 cm. Body proportions continue to change to more familiar ones. The face has a well-defined forehead, nose, cheeks and chin. The first hair appears on the head (very thin and colorless). The surface of the body is covered with vellus hairs, which retain skin lubrication and thereby perform protective functions.

The musculoskeletal system of the fetus is improved. Bones become stronger. Motor activity increases: the fetus can turn over, bend, and make swimming movements.

Development of the kidneys, bladder and ureters is complete. The kidneys begin to secrete urine, which mixes with the amniotic fluid.

: pancreatic cells begin to work, producing insulin, and pituitary cells.

Changes in the genital organs appear. In boys, the prostate gland forms; in girls, the ovaries migrate into the pelvic cavity. At the fourteenth week, with a good sensitive ultrasound machine, it is already possible to determine the sex of the child.

Fifteenth week (99-105 days)

Coccygeal-parietal size of the fetus is about 10 cm, fruit weight – 70-75 grams. The head still remains quite large, but the growth of the arms, legs and torso begins to outstrip it.

The circulatory system is improved. In the fourth month, a child’s blood type and Rh factor can already be determined. Blood vessels (veins, arteries, capillaries) grow in length and their walls become stronger.

The production of original feces (meconium) begins. This is due to the ingestion of amniotic fluid, which enters the stomach, then into the intestines and fills it.

Fully formed fingers and toes, an individual design appears on them.

Sixteenth week (106-112 days)

The weight of the fetus increases to 100 grams, the coccygeal-parietal size - up to 12 cm.

By the end of the sixteenth week, the fetus is already fully formed, he has all the organs and systems. The kidneys are actively working, a small amount of urine is released into the amniotic fluid every hour.

The skin of the fetus is very thin, subcutaneous fatty tissue is practically absent, so blood vessels are visible through the skin. The skin appears bright red, covered with vellus hairs and grease. Eyebrows and eyelashes are well defined. Nails are formed, but they only cover the edge of the nail phalanx.

Facial muscles are formed, and the fetus begins to “grimace”: frowning of the eyebrows and a semblance of a smile are observed.

Fetal development in the fifth obstetric month (17-20 weeks)

Seventeenth week (days 113-119)

The weight of the fetus is 120-150 grams, the coccygeal-parietal size is 14-15 cm.

The skin remains very thin, but subcutaneous fatty tissue begins to develop under it. The development of baby teeth continues, which are covered with dentin. The embryos of permanent teeth begin to form under them.

There is a reaction to sound stimuli. From this week we can say for sure that the child began to hear. When strong sharp sounds appear, the fetus begins to actively move.

Fetal position changes. The head is raised and is almost in vertical position. Arms bent in elbow joints, fingers clenched into a fist almost all the time. Periodically, the child begins to suck his thumb.

The heartbeat becomes clear. From now on, the doctor can listen to him using a stethoscope.

Eighteenth week (120-126 days)

The child's weight is about 200 grams, length - up to 20 cm.

The formation of sleep and wakefulness begins. Most of the time the fetus sleeps, movements stop during this time.

At this time, the woman may already begin to feel the baby moving, especially with repeated pregnancies. The first movements are felt as gentle jolts. A woman may feel more active movements when she is nervous or stressed, which affects the emotional state of the child. At this stage, the norm is about ten episodes of fetal movement per day.

Nineteenth week (127-133 days)

The child’s weight increases to 250-300 grams, body length – to 22-23 cm. The proportions of the body change: the head lags behind the body in growth, the arms and legs begin to lengthen.

Movements become more frequent and noticeable. They can be felt not only by the woman herself, but also by other people by placing their hand on their stomach. Primigravidas at this time can only begin to feel movements.

The endocrine system is improved: the pancreas, pituitary gland, adrenal glands, gonads, thyroid and parathyroid glands are actively functioning.

Blood composition has changed: In addition to erythrocytes and leukocytes, the blood contains monocytes and lymphocytes. The spleen begins to take part in hematopoiesis.

Twentieth week (134-140 days)

Body length increases to 23-25 ​​cm, weight – up to 340 grams.

The fetal skin is still thin, covered with protective lubricant and vellus hairs, which can persist until childbirth. Subcutaneous fatty tissue develops intensively.

Well formed eyes, at twenty weeks the blink reflex begins to appear.

Improved movement coordination: The child confidently brings his finger to his mouth and begins to suck it. Facial expressions are pronounced: the fetus may close its eyes, smile, or frown.

This week all women are already feeling movements., regardless of the number of pregnancies. Movement activity varies throughout the day. When stimuli appear (loud sounds, stuffy rooms), the child begins to move very violently and actively.

Fetal development in the sixth obstetric month (21-24 weeks)

Twenty-first week (days 141-147)

Body weight grows to 380 grams, fetal length – up to 27 cm.

The layer of subcutaneous tissue increases. The skin of the fetus is wrinkled, with many folds.

Fetal movements become more active and tangible. The fetus moves freely in the uterine cavity: it lies head down or buttocks, across the uterus. Can pull on the umbilical cord, push off the walls of the uterus with hands and feet.

Changes in sleep and wakefulness patterns. Now the fetus spends less time sleeping (16-20 hours).

Twenty-second week (148-154 days)

At week 22, the size of the fetus increases to 28 cm, weight - up to 450-500 grams. The size of the head becomes proportional to the body and limbs. The legs are bent almost all the time.

The fetal spine is fully formed: It has all the vertebrae, ligaments and joints. The process of strengthening bones continues.

Improves the fetal nervous system: The brain already contains all the nerve cells (neurons) and has a mass of about 100 grams. The child begins to take an interest in his body: he feels his face, arms, legs, tilts his head, brings his fingers to his mouth.

Heart size increases significantly, the functionality of the cardiovascular system is improved.

Twenty-third week (155-161 days)

The length of the fetal body is 28-30 cm, weight is about 500 grams. Pigment begins to be synthesized in the skin, resulting in the skin becoming bright red. The subcutaneous fatty tissue is still quite thin, as a result the child looks very thin and wrinkled. The lubricant covers the entire skin and is more abundant in the folds of the body (elbow, axillary, inguinal, etc. folds).

Development of internal genital organs continues: in boys - the scrotum, in girls - the ovaries.

Respiratory frequency increases up to 50-60 times per minute.

The swallowing reflex is still well developed: the child constantly swallows amniotic fluid with particles of protective skin lubricant. The liquid part of the amniotic fluid is absorbed into the blood, leaving a thick green-black substance (meconium) in the intestines. Normally, the bowel should not have a bowel movement until the baby is born. Sometimes swallowing water causes hiccups in the fetus; a woman can feel it in the form of rhythmic movements for several minutes.

Twenty-fourth week (162-168 days)

By the end of this week, the weight of the fetus increases to 600 grams, body length to 30-32 cm.

The movements are becoming stronger and clearer. The fetus takes up almost all the space in the uterus, but can still change position and turn over. Muscles grow rapidly.

By the end of the sixth month, the child has well-developed sense organs. Vision begins to function. If a bright light hits a woman’s belly, the fetus begins to turn away and closes her eyelids tightly. Hearing is well developed. The fetus determines pleasant and unpleasant sounds for itself and reacts to them differently. When hearing pleasant sounds, the child behaves calmly, his movements become calm and measured. When unpleasant sounds occur, it begins to freeze or, conversely, moves very actively.

An emotional connection is established between mother and child. If a woman experiences negative emotions (fear, anxiety, melancholy), the child begins to experience similar feelings.

Fetal development in the seventh obstetric month (25-28 weeks)

Twenty-fifth week (169-175 days)

The length of the fetus is 30-34 cm, body weight increases to 650-700 grams. The skin becomes elastic, the number and severity of folds decreases due to the accumulation of subcutaneous fatty tissue. The skin remains thin with a large number of capillaries, giving it a red color.

The face has a familiar appearance to a person: eyes, eyelids, eyebrows, eyelashes, cheeks, ears are well defined. The cartilage of the ears remains thin and soft, their bends and curls are not fully formed.

Bone marrow develops intensively, which takes on the main role in hematopoiesis. The strengthening of the fetal bones continues.

Important processes occur in lung maturation: small elements of lung tissue (alveoli) are formed. Before the baby is born, they are without air and resemble deflated balloons, which straighten out only after the first cry of the newborn. From week 25, the alveoli begin to produce a special substance (surfactant) necessary to maintain their shape.

Twenty-sixth week (176-182 days)

The length of the fruit is about 35 cm, the weight increases to 750-760 grams. The growth of muscle tissue and subcutaneous fat continues. Bones are strengthened and permanent teeth continue to develop.

The formation of the genital organs continues. In boys, the testicles begin to descend into the scrotum (the process lasts 3-4 weeks). In girls, the formation of the external genitalia and vagina is completed.

Improved sense organs. The child develops a sense of smell (smell).

Twenty-seventh week (183-189 days)

Weight increases to 850 grams, body length - up to 37 cm.

The organs of the endocrine system are actively functioning, in particular the pancreas, pituitary gland and thyroid gland.

The fruit is quite active, makes freely various movements inside the uterus.

From the twenty-seventh week in the child individual metabolism begins to form.

Twenty-eighth week (190-196 days)

The child’s weight increases to 950 grams, body length – 38 cm.

By this age the fetus becomes practically viable. In the absence of organ pathology, a child with good care and treatment can survive.

Subcutaneous fat continues to accumulate. The skin is still red in color, the vellus hair begins to gradually fall out, remaining only on the back and shoulders. Eyebrows, eyelashes, and hair on the head become darker. The child begins to open his eyes frequently. The cartilage of the nose and ears remains soft. The nails do not yet reach the edge of the nail phalanx.

This week starts more one of the cerebral hemispheres is actively functioning. If the right hemisphere becomes active, then the child becomes left-handed; if the left hemisphere becomes active, then right-handedness develops.

Fetal development in the eighth month (29-32 weeks)

Twenty-ninth week (197-203 days)

The weight of the fetus is about 1200 grams, the height increases to 39 cm.

The baby has already grown enough and takes up almost all the space in the uterus. Movements become less chaotic. The movements manifest themselves in the form of periodic kicks with the legs and arms. The fetus begins to take a definite position in the uterus: head or buttocks down.

All organ systems continue to improve. The kidneys already secrete up to 500 ml of urine per day. The load on the cardiovascular system increases. The blood circulation of the fetus is still significantly different from the blood circulation of the newborn.

Thirtieth week (204-210 days)

Body weight increases to 1300-1350 grams, height remains approximately the same - about 38-39 cm.

Subcutaneous fat tissue constantly accumulates, skin folds straighten out. The child adapts to the lack of space and takes a certain position: curls up, arms and legs crossed. The skin still has a bright color, the amount of grease and vellus hair decreases.

Alveolar development and surfactant production continues. The lungs prepare for the birth of the baby and the start of breathing.

Brain development continues brain, the number of convolutions and the area of ​​the cortex increases.

Thirty-first week (211-217 days)

The child's weight is about 1500-1700 grams, height increases to 40 cm.

Your child's sleep and wake patterns change. Sleep still takes a long time, during which time there is no motor activity of the fetus. While awake, the child actively moves and pushes.

Fully formed eyes. During sleep, the child closes his eyes, while awake, the eyes are open, and the child blinks periodically. All children have the same iris color ( blue color), then after birth it begins to change. The fetus reacts to bright light by constricting or dilating the pupil.

Brain size increases. Now its volume is about 25% of the volume of the adult brain.

Thirty-second week (218-224 days)

The child's height is about 42 cm, weight - 1700-1800 grams.

Accumulation of subcutaneous fat continues, due to which the skin becomes lighter, there are practically no folds left on it.

Internal organs are improved: organs of the endocrine system intensively secrete hormones, surfactant accumulates in the lungs.

The fetus produces a special hormone, which promotes the formation of estrogen in the mother’s body, as a result, the mammary glands begin to prepare for milk production.

Fetal development in the ninth month (33-36 weeks)

Thirty-third week (225-231 days)

The weight of the fetus increases to 1900-2000 grams, the height is about 43-44 cm.

Skin becomes increasingly lighter and smoother, the layer of fatty tissue increases. The vellus hair is increasingly wiped off, and the layer of protective lubricant, on the contrary, increases. Nails grow to the edge of the nail phalanx.

The baby becomes increasingly cramped in the uterine cavity, so his movements become more rare, but strong. The position of the fetus is fixed (head or buttocks down), the likelihood that the child will turn over after this period is extremely small.

The functioning of internal organs is becoming more and more improved: the mass of the heart increases, the formation of the alveoli is almost complete, the tone of the blood vessels increases, the brain is fully formed.

Thirty-fourth week (232-238 days)

The child's weight ranges from 2000 to 2500 grams, height is about 44-45 cm.

The baby now occupies a stable position in the uterus. The bones of the skull are soft and mobile thanks to the fontanelles, which can close only a few months after birth.

Head hair grows rapidly and take on a certain color. However, hair color may change after childbirth.

Intensive strengthening of bones is noted, in connection with this, the fetus begins to take calcium from the mother’s body (the woman may notice the appearance of cramps at this time).

The child constantly swallows amniotic fluid, thereby stimulating the gastrointestinal tract and kidney function, which secrete at least 600 ml of clear urine per day.

Thirty-fifth week (239-245 days)

Every day the child gains 25-35 grams. Weight during this period can vary greatly and by the end of the week it is 2200-2700 grams. Height increases to 46 cm.

All internal organs of the child continue to improve, preparing the body for the upcoming extrauterine existence.

Fatty tissue is intensively deposited, the child becomes more well-fed. The amount of vellus hair is greatly reduced. The nails have already reached the tips of the nail phalanges.

A sufficient amount of meconium has already accumulated in the fetal intestines, which normally should go away 6-7 hours after birth.

Thirty-sixth week (246-252 days)

The weight of a child varies greatly and can range from 2000 to 3000 grams, height - within 46-48 cm

The fetus already has well-developed subcutaneous fatty tissue, skin color becomes lighter, wrinkles and folds disappear completely.

The baby occupies a certain position in the uterus: more often he lies upside down (less often, with his legs or buttocks, in some cases, transversely), his head is bent, his chin is pressed to his chest, his arms and legs are pressed to his body.

Skull bones, unlike other bones, remain soft, with cracks (fontanelles), which will allow the baby's head to be more pliable when passing through the birth canal.

All organs and systems are fully developed for the existence of a child outside the womb.

Fetal development in the tenth obstetric month

Thirty-seventh week (254-259 days)

The child's height increases to 48-49 cm, weight can fluctuate significantly. The skin has become lighter and thicker, the fat layer increases every day by 14-15 grams per day.

Cartilages of the nose and ears become denser and more elastic.

Fully lungs are formed and mature, the alveoli contain the necessary amount of surfactant for the newborn to breathe.

The digestive system has matured: Contractions occur in the stomach and intestines to push food through (peristalsis).

Thirty-eighth week (260-266 days)

A child's weight and height vary greatly.

The fetus is fully mature and ready to be born. Externally, the child looks like a full-term newborn. The skin is light, the fatty tissue is sufficiently developed, and vellus hair is practically absent.

Thirty-ninth week (267-273 days)

Typically two weeks before birth the fruit begins to descend, pressing against the pelvic bones. The child has already reached full maturity. The placenta begins to gradually age and its metabolic processes deteriorate.

The weight of the fetus increases significantly (30-35 grams per day). The proportions of the body change completely: the chest and shoulder girdle are well developed, the belly is round, and the limbs are long.

Well developed sense organs: the child catches all sounds, sees bright colors, can focus vision, taste buds are developed.

Fortieth week (274-280 days)

All indicators of fetal development correspond to new to the awaited one. The baby is completely ready for birth. The weight can vary significantly: from 250 to 4000 and above grams.

The uterus begins to periodically contract(), which is manifested by aching pain in the lower abdomen. The cervix opens slightly, and the fetal head is pressed closer to the pelvic cavity.

The skull bones are still soft and pliable, which allows the baby’s head to change shape and pass the birth canal more easily.

Fetal development by week of pregnancy - Video

Biological and social factors influencing gender identification are so closely related that it is difficult to understand them. When a child is born to parents, in modern times it is already known in advance what gender it will be, but if the mother did not know this before giving birth. What a thirst she would have then to find out the sex of the baby as quickly as possible. This happens because parents treat their children differently depending on their gender. Thus, the behavior of mom and dad gives the child an incentive to learn more about himself by identifying himself by gender.

After conception, the process of formation of sexual characteristics in the embryo occurs. United, female and men's cells combine their chromosomes, 23 each from the sperm and egg, into a new organism. This gives a total of 46 chromosomes. A female cell always carries an X chromosome, and a male spermatozoon either Y or X. Thus, the female code is XX, and the male XY is male.

Further in the development of the embryo, the stage of formation of the gonads takes place. This occurs in the sixth week of pregnancy. Before this period, it is impossible to determine the fetus. A male embryo occurs when a male chromosome is present. The H-Y antigen, which is responsible for the male genetic code, must be present here. The absence of this antigen indicates that the sex of the child will be female.

The appearance of the genital organs occurs after the stage of formation of the gonads with the help of hormones. This stage begins at 8-9 weeks of pregnancy. When the amount of testosterone produced is greater, the gender is determined to be male. Both female and male bodies contain hormones of both sexes, however, large quantity a certain hormone indicates a specific gender.

The process of intrauterine development of the fetus involves the influence of androgens on it (hormones that play a decisive role in the occurrence of secondary sexual characteristics in both one and the other sex, for example, a rough voice, “vegetation” on the face and the whole body. As in all men, increased secretion sweat, elongation of the penis, formation of the face and body skeleton according to the male type, increase in the size of the prostate and the amount of its secretion). If androgens do not have a sufficient effect on the fetus, then a girl will be born. In the first period, the formation of the genital organ occurs. Then comes the creation of the brain's sexual orientation. The stage of formation of the male or female hypothalamus is underway.

Laying of external organs

Laying the internal organs:

1. During the initial 6 weeks of pregnancy, male and female embryos cannot be distinguished;
2. Only after 8 weeks of pregnancy, the testes of an embryo with the sexual characteristics of a boy release testosterone and an inhibitor of the Müllerian ducts, leading to the disappearance of the ducts themselves. In the absence of male hormones, the Müllerian ducts (a double canal with a connected distal part, which appears after the end of the second month of development of the embryo inside the mother from the grooves that serve as the demarcating role of the epithelium) begin to transform into female organs. The Wolffian ducts (structures in the fetus that subsequently develop into the male genital organs located inside) cease to exist.
3. After 9 months of pregnancy in the female fetus, the Müllerian duct turns into fallopian tubes, and in the male fetus, the glands pass into the scrotum.

Video of how a baby’s gender is determined

When planning a pregnancy, many parents ask the question: what determines the sex of the child? Part married couples I would like to be able to choose whether to have a girl or a boy. Because of this desire, myths arise that certain factors, such as the age of the spouses, diet or zodiac sign, influence the gender of the unborn child.

But is this really so? To understand, you need to understand how the fertilization process occurs and whether it is possible to intervene in it. Modern medical technologies come to the aid of young parents. It is possible that soon the sex of the child will be “ordered” in the laboratory.

To understand what determines the sex of a child, you need to remember the basics of genetics from a school biology course. So, every cell in the body has a nucleus - a structure that contains DNA (genetic information).

All human characteristics: hair color, eyes, gender, body type, etc. are determined by a set of genes and chromosomes. It is different for women and men. There are 23 pairs of chromosomes in one cell, 22 of them are identical (XX), and the structure of the latter depends on gender. In a female body it looks like XX, and in a male body it looks like XY.

All cells in the body, except sex cells, contain a paired set of chromosomes. And eggs and sperm are single. In the process of formation of germ cells, paired sets are separated.

Thus, all eggs contain 23 single chromosomes, and the last one is X. And all sperm also contain 23 chromosomes, but the last one can be X or Y - both equally.

Depending on what set is in the sperm that fertilizes the egg, a boy (Y) or a girl (X) will be born.

If all sperm had the same properties, then the probability of conceiving a child of a certain gender would be 50%. But male reproductive cells behave differently. Y sperm move faster but are less resilient. X-sperm are not as active, but they are better able to withstand the influence of factors in the internal environment of the female reproductive system.

Factors influencing the gender of the unborn child

There are certain factors whose influence on the sex of the unborn child is explained from a scientific point of view:

1. Time of conception. The most studied and reliable factor. As already noted, male sperm differ in the degree of activity and vitality: Y - move faster and die more easily, X - slow, but more resilient. It has been established that sperm in a woman’s body can remain active for up to 5-7 days. If sexual intercourse occurs during ovulation, then the fastest Y-sperm will fertilize the egg, but if it occurs a few days earlier, then the most viable X-sperm have a better chance. Therefore, planning the sex of the child comes down to determining the day of ovulation.
2. Position during sexual intercourse. This factor is also associated with different activities of X- and Y-spermatozoa. During an act with deep penetration of the penis, the distance to the egg is reduced. Under such conditions, fast Y sperm have a better chance of fusion. Since the distance to be overcome is not long, they do not have time to die. If the penetration is shallow, then the sperm need to “travel” a greater distance and not the fastest, but the strongest, that is, X-sperm, survive along the way.
3. Parents' sexual activity. With frequent intercourse (daily or every other day), the likelihood that Y-sperm will fertilize the egg is higher - there are high chances that sexual intercourse will occur on the day of ovulation. If the sexual activity of the spouses is low, then X-sperm will be able to survive until ovulation, as they remain active for up to 7 days.

The most common myths

In addition to factors whose influence on the gender of the unborn child is scientifically confirmed, there are myths - ideas that claim that you can conceive a son or daughter by following ancient tables, focusing on the zodiac signs of your parents, adhering to a special diet, etc.

The following versions about what determines the sex of a child are most widespread:

1. “Installation” of a woman’s body. According to this myth, once every 3 years the female body “switches” from the birth of a boy to the birth of a girl. It turns out that only the gender of the first child cannot be planned, and after his birth everything comes down to simple arithmetic calculations. In fact, gender is determined by sperm, that is, the material of the father.
2. "Fresh" blood of the parent. This myth is based on the assumption that a person's blood renews itself after a certain number of years. And the sex of the child will be the same as that of the parent with more “fresh” blood. This theory has nothing to do with the physiology of the human body; the properties of blood do not affect the process of conception.
3. “Strong” sex cell. Proponents of this theory are confident that at certain periods of life, eggs in women and sperm in men become “stronger” or “weaker.” And depending on this, a girl or a boy is born. In fact, it may matter which sperm turns out to be more viable and active, but the “strength” of the egg does not affect the fertilization process.
4. Diet. This assumption is based on the fact that the diet of the spouses several months before conception can affect the sex of the child. In fact, eating certain foods has no effect on the process of conception.
5. Oriental, Chinese and Japanese ancient tables. All of them involve complex calculations, which, however, are not related to the woman’s monthly cycle or the characteristics of the reproductive systems of the spouses.
6. Zodiac signs. There are male and female zodiac signs. The theory states that if the future mother and father have a masculine sign, then a girl will be born. If both spouses have female sign, then a boy will appear. Such assumptions are not scientifically substantiated in any way.

Is it possible to plan the gender of the unborn child?

According to statistics, on average, 105 boys are born for every 100 girls around the world. This may be due to the different survival rates of the two sexes, although modern medicine makes this difference insignificant.

Technology has developed rapidly over the past decades artificial insemination oocytes and embryo culture. Since the process of fusion of germ cells can be taken outside the female body, it becomes possible to influence it.

Today, there are several technologies that allow you to plan the sex of your unborn child:

1. Robert Erickson's method. Its essence is that sperm are divided into fractions with Y- and X-chromosomes. First, the day of ovulation in a woman is determined. The man collects genetic material (sperm), which is treated with a drug containing albumin. It has been noticed that cells with Y chromosomes pass through the protein barrier faster and are the first to reach the bottom of the test tube. Then the specialist separates the necessary fractions and performs artificial insemination.
2. Flow laser sorting of spermatozoa. The separation of male reproductive cells is performed using a laser beam. Sperm with Y chromosomes contain 3% less genetic material than with X chromosomes. The latter can be eliminated when exposed to a laser. When planning a girl, this method is 90% effective, and if you want a boy – 70%. The required part of the sperm (screened out or remaining) is injected into the uterus or fertilization is carried out under artificial conditions (in vitro).
3. Preimplantation diagnosis. Such a study is carried out at a certain stage of embryo cultivation. In other words, sperm and eggs are collected first. Then, under artificial conditions, the process of fertilization occurs. After a few days, embryonic cells can be examined for the presence of genetic pathologies and to determine sex. Material carrying the required combination of sex chromosomes: XX or XY is transplanted into the uterus. It should be noted that preimplantation diagnosis is associated with risks, therefore, in order to determine the sex of the unborn child, it is not carried out in Russia.

The development of methods for planning the gender of a child is complicated not only by the level of technological development, but also by ethical considerations. After all, the balance established by nature - 100 girls to 105 boys - exists for a reason.

Cannot be determined by calendar auspicious days for conception, the shape of the pregnant woman’s abdomen and other indirect signs. Only a doctor can find out exactly whether a boy or a girl will be born to parents in 9 months, using various diagnostic methods.

When can you find out the sex of a child? frequently asked questions, which are heard by family planning clinic specialists and gynecologists in antenatal clinics. And only a small part of future parents prefer to remain in the dark until the birth. In rare cases, determining the sex of the fetus is important from a medical point of view, for example, when one or both parents have genes that cause severe diseases that are transmitted only to boys/girls.

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A person’s gender is determined at the moment of fusion of the mother’s egg and the father’s sperm. The key carrier of genetic information that determines gender the future person is the sperm. An egg initially has only a female chromosome, while a sperm can have one of two chromosomes - a female X (X) or a male Y (Y).

If the egg is fertilized by a sperm carrying the X chromosome, the sex of the baby will be female. A boy will be born if the sperm carries a Y chromosome.

Any specialist who knows the stages of fetal development in all trimesters of pregnancy can answer future parents.

1. The child’s genitals begin to form at 11 weeks, when a small labioscrotal tubercle appears between the legs at the site of the future genital organs in boys and girls. Over the next two weeks, under the influence of the hormone dihydrosterone, the formation of the penis occurs. The testicles are still in the pelvic cavity, and later descend into the scrotum.
2. Theoretically, 10-11 weeks is the minimum period when the sex of the child is found out during pregnancy. Using an ultrasound of the uterus, a gynecologist can see the tubercle and preliminarily determine the gender of the fetus. But the possibility of error at this time is 50%.
3. More accurate data about the baby’s gender can be obtained after the 18th week, when the male or female external genitalia are already well formed.
4. But the most optimal period when you can determine the sex of a child during pregnancy is 24-25 weeks. At this time, the specialist can tell for sure whether it is a boy or a girl.

The picture shows what can be seen on a fetal ultrasound and at what time

The main method for diagnosing the sexual characteristics of the fetus is ultrasound examination of the uterus. Modern ultrasound machines allow you to obtain a three-dimensional color image and accurately determine the gender of the fetus. By using ultrasound examination the doctor visually determines the sex of the fetus. If this is difficult (for example, if a girl has swelling of the labia that resembles a boy's testicles), then the specialist can measure the angle between the genital tubercle and the fetal spine. For a boy, the angle exceeds 30 degrees; for a girl, it is usually less than 30.

But sometimes 10 weeks is not the earliest period of time after conception, after which you can find out the gender of the unborn child.

Minimally invasive diagnostic methods are used extremely rarely - a biopsy of amniotic fluid (amniocentesis) and taking blood from the umbilical cord (cordocentesis).

By studying these biological materials, you can find out the sex of the baby with 100% accuracy, starting from the 7th week. But both procedures are used exclusively for medical reasons, when there is a risk of transmitting diseases or genetic mutations that appear depending on the sex of the fetus.

Difference in angles on ultrasound in a boy and a girl

Are there mistakes?

Mistakes in determination sometimes happen. The more early date pregnancy, the higher the likelihood of misdiagnosis by a specialist. The fetal labial-scrotal tubercle begins to transform into a penis after the 11th week, but even at this time the individual structural features of the fetal genitalia can mislead the doctor. Sometimes even an experienced specialist cannot distinguish a girl’s labia majora from a boy’s testicles, and a specialist may confuse a slowly developing penis with the clitoris.

Often the fetus itself makes diagnosis difficult by turning away or crossing its legs, covering the genital area. Theoretically, parents can ask the gynecologist to pre-determine the gender of their child, starting from the 11th week, but they need to make allowances for the individual characteristics of the fetus’ development and be prepared for a surprise.

Knowing when you can find out the gender of your baby for sure, it’s better to calmly wait until the end of 24 weeks to find out exactly the gender of your baby.

Is it possible to accurately find out the sex of a child during pregnancy?

It is possible to determine the sex of the unborn child before birth not only with the help of ultrasound. Modern DNA testing technologies make it possible to determine the gender of a child. When can you accurately find out the gender of a child using the mother’s blood? This is possible already from the 4th week of pregnancy.

For this, the mother's blood is needed: it contains part of the genetic material of the fetus - it is examined to determine the set of chromosomes. If a Y chromosome is found in it, the sex of the child will be male. If the Y chromosome is not detected in the blood, then the fetus is female. The accuracy of this method is very high - 99%. The disadvantage of this method is its high cost.

You can also resort to, by which the sex of the unborn child is determined based on the age of the mother and the day of conception. But this method does not provide a 100% guarantee, since it has no scientific basis.

Useful video

More information about methods for determining the sex of an unborn child, when and how this can be done:

Conclusion

1. The end of the 10th - beginning of the 11th week of pregnancy is the earliest time at which the sex of the child is found out. At this time, the labioscrotal tubercle begins to transform into male or female external genitalia.
2. Until the 18th week, the probability of an erroneous diagnosis on ultrasound is 50%, because Individual characteristics of fetal development may determine the slow formation and small size of male genitalia.
3. Week 25 is the optimal time to find out the sex of the baby using an ultrasound.
4. Using a DNA test in the mother's blood, the Y chromosome of a male fetus can be detected from the 4th week of pregnancy.

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