Usual pregnancy lasts on average 266 days. During this time the future baby from a barely perceptible point should turn into a real person and after birth move to a relatively autonomous existence. How does the miracle of the conception of the unborn child take place, what changes occur with the embryo at different periods of its bearing, when the organs and life support systems of crumbs are laid?
When ejaculation (ejaculation) in the vagina fall from 140 to 350 million spermatozoa. And each of them could become a little man after the merger with the egg. But the law of natural selection comes into force: only about 200 of the hardiest of them will go through a difficult path to the fallopian tube and will meet with the ovum that leaves the ovary during ovulation. A few units will break through through its outer shell, and only one will be able to bring the matter to its end and fertilize it.
As soon as the spermatozoon is inside the egg cell, they merge, that is, fertilization. Now it is no longer a sperm and an ovum separately, but a single cell is a zygote. Soon it will begin to divide, forming two cells. Conception has taken place, the development of the future kid has been laid. Depending on the stage of intrauterine life, doctors call the future child a zygote (unicellular organism), a blastocyst (or blastomer - an organism of 16 or more cells), an embryo (from implantation into the uterine wall before 9-10th week of pregnancy) and a fetus -10th week of pregnancy before birth). But for mom, it's still a favorite and long-awaited baby.First days
Zygote - a cell with a double set of chromosomes - moves along the uterine tube towards the uterus and is divided into 2, 4, 6, 8, etc. cells, forming blastomere tightly connected with each other by a constriction. Each of them has all the data to become a separate organism. In most cases at this stage it is decided how many babies will be born - 1 or 2. If the blastocysts are completely separated from each other, a woman can become the mother of identical twins.The egg is one of the largest cells in the body. She carries a supply of nutrients in the form of yolks, which the embryo suffices for the first 3-4 days of life.
After 3-4 days the embryo is in the uterine cavity. Approximately at the end of the first - the beginning of the second week of the existence of a new life, the embryo, consisting of 100 cells and having the shape of a ball, is implanted into the wall of the uterus. After this, the largest blastomeres will give rise to the embryo, and the rest will turn into a nutrient shell, part of which will later become the placenta.
An implant in the uterus of the blastocyst begins intensive cell division. Gradually, the embryo becomes like a disk. At a period of 2-3 weeks, rudiments of all internal organs are formed. The heart is formed first. A fetal egg (a fetal bladder with an embryo and amniotic fluid) can already be seen with transvaginal ultrasound. (that is, the doctor may determine pregnancy when researching).Responsible period
In 3-6 weeks there comes a very responsible period: at this time the organs and tissues of the future baby are actively differentiated. Hardly that not so - in the program enclosed by the nature the failure can occur. The shape of the embryo resembles a tube, and it is very similar to a fish: there is a tail, something resembling the head, gill slits and the like of fins. From the fins, then limbs will develop, and from the "gill slits" - respiratory organs.
From 21 days from the moment of conception, the embryo begins to develop its own circulatory system. Also, the "fish" is actively formed by the nervous system, reflexes, kidneys, adrenals; the liver is taken to create blood cells.
At the 5th week during ultrasound, the doctor sees an embryo 5-7 mm long and can hear a heartbeat with a frequency of 120-130 beats per minute.
At the 7-8th week the future baby is already like a little man. He grew to 3 cm. Although he weighs less than a letter in an envelope, he has already formed the rudiments of all future organs. The head is more torso and tilted to the chest. At this time, the face, eyes and ears are formed. Gradually, eyes appear on the eyes, and on the handles and legs - fingers. The future crumb can already open and close the mouth. Develop sexual organs. The endocrine system begins to work autonomously: in the analysis of the mother's blood, hormones produced by the pituitary gland of the future baby are found. The thyroid gland begins to function. The only organ that by that time was almost completely formed was the heart. He has two atriums and a ventricle. Thanks to ultrasound, you can already see the spine and observe how the embryo moves.I see you
From the 9th to the 10th week, doctors call the human embryo a fruit. He improves the skeleton, a sucking reflex appears. Greetings from our distant ancestors - the tail - disappears. On ultrasound see a tiny little man 17-22 mm long. The trunk on this term grows faster, the head - more slowly. It is perfectly visible on ultrasound.
He is still very, very vulnerable and can not resist infection. It is especially sensitive to the rubella virus. If the future mother is sick with rubella, there is a danger of anomalies in the development of the future baby - the occurrence of heart defects, eyes, hearing and brain. At the 10th week, these anomalies can be determined by ultrasound - therefore at the 10th-13th week prenatal screenings are usually conducted to identify developmental defects.
At 10-13 weeks on the handles and legs formed fingers, continue to develop eye and neck. The future child can move handles, legs and even turn his head. The rudiments of teeth and nails are formed. From the 11th week he tries to breathe, which increases the flow of blood to the heart. The kidneys begin to excrete urine, which enters the amniotic fluid. So, the little man can urinate. The face of the crumb gets human traits. The bone marrow and the immune system work. The future baby is noticeably "grown up": its length is 7-9 cm and its weight is 20-25 g. Sometimes during ultrasound it is already possible to tell who the future parents are waiting for - a boy or a girl.Middle of pregnancy
By the end of the 16th week all the internal organs of the crumb are quite clearly visible on the ultrasound. And even then the doctor makes the final clarification of who to expect - a son or daughter. The main thing is that the baby turns to the doctor the right place.
At the beginning of the second trimester, the coagulation system of blood begins to form. If a woman at this time blood acquires an increased ability to clot (so her body is preparing for childbirth), then the future baby coagulation is still very weak. But it is already possible to determine the blood group and Rh factor, and therefore, to prevent Rh-conflict.
The child "grew" already up to 16 cm and weighs 200 g. During this period, his head seems disproportionately large relative to the torso. Gradually, the little bit learns to own handles and legs, begins to swallow the amniotic fluid, actively sucking a finger. The cells of the brain are divided at the maximum speed, both hemispheres are already formed, furrows and convolutions appear. The cortex is about to form. The heart contracted with almost the same frequency as in newborns. The organs of the digestive tract, the thyroid and pancreas, started working.
From this time the baby hears sounds. Which ones - on this account there are different opinions. Some researchers are sure that before birth a child hears lower sounds better. Others believe that in the abdomen of the mother, the future carapace hears just the mother's voice, and 8-10 times better than the voices of the people around her. That is why when he is born, he begins to recognize it before other voices of people close to him.Let's make faces
At 16-20 weeks, a woman first feels the movement of the child. It is believed that earlier it is felt by women who have already given birth. Strange as it may seem, the future baby shows the greatest activity when the mother is resting. In addition, he begins to react to external stimuli: for example, when the mother is upset, begins to "kick" hard.
Approximately from the 18-20th week, the baby's heartbeat can be heard with the help of a midwife stethoscope. The skin of a small man is thin, red, with abundant downy. Delicate thin hairs will fall about a month before birth. The muscles of the face are formed, and the crumb begins to actively build faces: winks, frowns, opens her mouth. He had eyebrows! The taste buds are formed on the tongue.
In the skin, the sebaceous glands function, they release a lubricant that covers the baby's body abundantly and protects the delicate skin from adverse effects. The intestines work, and in it forms meconium - the original feces. If a woman is waiting for the twins, then from this period they can touch each other's faces and even hold hands. The baby grows to 25 cm and weighs about 300 g.Sound Memory
According to recent research, the child remembers the sounds he hears while in his mother's abdomen, and gets used to them. So after the birth of a baby, it can calmly react even to harsh and annoying sounds, if heard during intrauterine life. For example, Japanese moms living near Osaka airport do not experience discomfort from the constant roar of aircraft engines and sleep peacefully. At the same time, the children of those parents who have moved to this place after the birth of their youngsters, during the take-offs and calls of aircraft to land, have difficulty falling asleep.Acrobatic exercises
At the 20-24th week, the baby begins to "round off" gradually: the layer of subcutaneous fat increases, and the skin is not as wrinkled as in the first trimester. Synthesis of the substances necessary for the development of surfactants begins, which, after the birth of the baby, will keep the lungs in a straightened state.
By the 24th week the baby can blink. He grew to 30 cm and weighs 600-680 g. The compact size allows him to actively "tumbling" in the uterus, but more and more often the crumb tries on the position of the head down - gradually preparing for the birth. On the next ultrasound the doctor can well consider the brain structures - gyruses and furrows.Modern studies of brain activity with the help of echography and electroencephalography found that already at the 25th week of gestation the future child before moving, activates one of the areas of the cortex of the brain. Similarly, it happens in adults. So this is no longer a simple reflex, but the beginnings of conscious activity.
At the 24th-28th week of pregnancy, the baby sets the rhythm of wakefulness and sleep. In accordance with them, the motor activity and heart rate and respiration rate change. The nails are still not fully formed and do not reach the end of the fingers, the cartilages of the nose and ears are soft, so it's too early to talk about their shape. The eggs are formed in boys, but they have not yet descended into the scrotum. In girls, large labia do not cover the small ones. The child knows how to squeeze the jaws, feels pain and reacts to it, it forms a swallowing and sucking reflexes.
At this time the growth of the baby is 35 cm, weight - not less than a kilogram.On the eve of birth
Before the birth of crumbs, nothing remained - most of the hard and very responsible way passed.With the help of modern equipment, it is established that an unborn child can do much. For example, he becomes more "voracious" if the future mother is addicted to sweet, catches the changes in the emotional state of a woman: if she is irritated, the pulse rate of the future baby grows; When my mother calms down, his pulse slows down.
In the third trimester, at the 28-32nd week, the baby can wake up with her mother in the morning and greet her with violent tremors.
By the 32nd week, a woman feels like a baby hiccup. In the uterus, the crumb is rather small, so the movements of its arms and legs become very palpable. The child finally decides that to be born more comfortable head first, and takes the corresponding position. At the same time, he begins to see. The skin of the baby is formed, the layer of subcutaneous fat is increased.
Children born before the term, on the 28-32 week of pregnancy, in most cases quickly catch up with their peers and then develop without any peculiarities: after all, all life support systems for them, although imperfect, but practically formed. The height of the baby is about 40 cm, weight - about 1600.
At the 33-37th week, the lungs are almost ready for independent work. The child is already quite large (height 45 cm, weight about 2.5 kg), and in the uterus it does not turn around. Movements are not as active as they were before.Readiness number one
From 37 to 41 weeks of labor can begin at any time. To them, everything is ready. The baby's head snuggled against the entrance to the small pelvis. In the intestine accumulated primary feces, in boys the testicles sank into the scrotum, the girls closed their small labia minors small. In the lungs, surfactants accumulated in such a quantity that, if the child is born, they will not let slip up easily and the baby can breathe on its own. The child is ready to take the first breath. Doctors say: it seems, the decision, when to appear on the white light, is taken by the baby. To whom, if not him, it is better to know whether he is ready to make the difficult path through the birth canal.To everything its time
Postnatal pregnancy is considered from 37 to 41 weeks. But even the baby born in the term almost all life support systems will be finally formed after his birth. For example, the immune system uses maternal antibodies obtained with breast milk for the first six months. In full force, it begins to work only to 1.5 years. The kidneys start to work effectively by the end of the first year of life. Until that time, they are unable to completely remove salt and protein metabolism products from the body. Therefore, it is so important to control the level of salt and protein in baby food. The liver starts to work 100% to two years. Intensive development of the cerebral cortex is completed by 7 years. The reproductive system ripens on average to 14-15 years, and the growth of the skeleton stops at 25 years.Read on this topic:
- Double solid: how to tell a man about pregnancy
- Who will you be born: a boy, or a girl
- How to maintain the beauty of the body in pregnancy