It is believed that a person's age is calculated from the day of his birth. This is not entirely true statement, because the birth of a human life begins at conception - it turns out that all people older than about a year of his chronological age. For the nine months, man who lives in the womb, greater and perhaps more varied throughout his later life. Child development during pregnancy - this is a very delicate mechanism, at this time there is a formation and laying his internal organs and systems, as well as hair color Hair: structure, characteristics of growth and development , Eyes, and other hereditary diseases.

First trimester of pregnancy

Obstetricians define a normal pregnancy is not nine, but ten months or forty weeks. The whole period of pregnancy is conditionally divided into three trimesters. The duration of the first trimester is fourteen - sixteen weeks from the day of conception Conception - as the emerging life   On the first day of pregnancy the egg meets the sperm, resulting in its fertilization and the formation of the zygote (Conception) .  In the next six - eight days, the zygote moves through the fallopian tube and into the uterus, where it was successfully attached to the mucosa (implantation) .  In the second week of pregnancy the embryo is separated from the membranes, which are beginning to produce amniotic fluid .  It is in this fluid (in childbirth - is water) and will be all the further development of the child .  Three weeks after conception the embryo there are the beginnings of the nervous and skeletal systems, and ultrasound determined his heartbeat .  Starting from the fifth week, the embryo is put head, arms, legs and a tail, and a length of about six millimeters it .  By the end of the eighth week of the unborn child are made thorax and abdomen, face appears, visible ears and vulva .  The length of the embryo in the period of about twenty millimeters .  At twelve weeks, the embryo has already formed the muscular system and is actively moving (which the expectant mother still does not feel) .  Its movements are quite aware, he turns his head, thumb-sucking, mouth open .  This term future child is already beginning to respond to external stimuli (formed by the vestibular system) .

At sixteen weeks of pregnancy, the placenta is fully formed and started functioning, fetal weight is one hundred and fifty grams, and growth - sixteen - eighteen centimeters.

The second trimester of pregnancy

The second trimester lasts from the sixteenth to the twenty-fourth week .  At twenty weeks, the fetus reaches the thirty centimeters in length, it already has nails on the fingers of hands and feet .  At about this time the expectant mother begins to feel the stirring of his, which at first is not very active (fetus floats in the amniotic fluid from wall to wall of the uterus), but sometimes an unexpected stimulus, the child is very active .  The doctor already well hear the fetal heartbeat through a stethoscope .  In the twenty-four weeks the child weighs five hundred grams, and his skin is very thin, red and wrinkled .  As a protective mask on her skin irritations appear vernix .  Ends with the formation of sweat and sebaceous glands, begins the maturation of the lungs and there is a small amount of fat .  Since the twenty-seventh week, the baby is already open and close his eyes and reacts to light through the front wall of the mother's abdomen .  At that time, he formed a sucking reflex, developed muscles of hands and feet .  Mom may determine periods of fetal activity (sleep and wakefulness) .  During the day, when a woman is busy with something, baby sleeps, and in the evening and at night, when the mother is resting, he begins to "run amok" .  The weight of the fetus is already eight grams, and growth - thirty-six centimeters .

The third trimester of pregnancy

The duration of the third trimester of the last fourteen weeks of pregnancy. On the twenty-eighth week fetus weighs about one kilogram, and the length of his thirty-five centimeters. He has already made all the senses, it is able to recognize his mother's voice. The baby's skin becomes more dense and thick and covered with soft fuzz (lanugo). At thirty-two weeks, the fetus reaches two kilos, it is fully formed subcutaneous tissue. During this period, it starts the formation of the immune system (antibodies to immunoglobulins obtained from the mother). Since the thirty-sixth week of pregnancy, the baby is ready for birth, every day he puts on weight (about fourteen grams), and hepatic accumulation of iron, necessary for blood formation. Lanugo this period disappears, your baby move decrease, and he is the head of the entrance to the pelvis.

Anna Sozinova

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