- Fetal development - week after week
- Heredity
- The fruit and its relationship with the mother
- Signs of fetal maturity
The fruit and its relationship with the mother
Fruit - a developing organism from the ninth week of fetal development before birth. Prior to the ninth week of this organism is known as a fetus or embryo. A normal pregnancy lasts 40 weeks, plus or minus two weeks. These 40 weeks gynecologists are divided into three trimesters: I trimester - up to 12 weeks, II - 12-24 weeks, III - from 24 weeks before birth.
The fruit is inextricably linked to the mother's body during pregnancy operating system mother - placenta - fetus. Parent body provides optimum conditions for the development of the fetus. In co-mother and fetus engage the nervous, endocrine, immune, and other mechanisms. The most complete body of mother and fetus begin to interact after the development of the placenta, which allows the fetus to adapt to the changing conditions of the mother's body.
The development of the fetus in the first trimester (12 weeks)
At the end of the fourth week of gestation the embryo is implanted into the mucosa of the uterus, where the formation of primordia and organs and membranes. At the end of the eighth week of pregnancy, embryo length is approximately 3 cm, it is already possible to distinguish a head, torso (length is equal to the head), limb buds, eyes, nose, mouth. According to the microscopic structure of the sex glands can determine the sex of the fetus.
At the end of the 12th week fetus reaches a length of 9 cm, weight - '40 clearly defined limbs, begins the formation of the external genitalia, can be seen on x-ray point of ossification in the cartilage skeleton.
The development of the fetus in the second trimester (12-24 weeks)
In the 16th week of fetal length of about 16 cm, weight about 120 grams, clearly visible floor, the skin is thin, smooth, reddish, without subcutaneous fat, his face almost formed, begins ossification of skull. In connection with the formation of muscle activity of limb movement grows, there are weak respiratory movements.
At the end of the 20th week fetus reaches a length of 25 cm, weight - 300 grams Movement is so active that they felt the mother and the fetal heart may be heard. The skin of the fetus starting with the head and face, covered with the finest vellus hair, and the whole body - vernix consisting of a mixture of fat-like sebum with the scales of the surface layer of the skin. In the intestine, a first cal - meconium. In the lower abdomen starts to be postponed subcutaneous tissue.
At the end of 24 weeks, the length of the fetus is 30 cm, and weight - 700 Internal organs mature enough, sometimes in appropriate specially created conditions fetus may be viable in preterm labor.
The development of the fetus in the third trimester (24 weeks before childbirth)
By the 30th week, the length of the fetus is about 35 cm, weight - about 1 kg. The fruit has a "senile" appearance due to poor development of the subcutaneous tissue, the whole body is covered with vellus hair, cartilage, the ears are very soft, nails do not reach the fingertips. In girls, the labia majora to close small, boys testicles are not descended into the scrotum, navel is closer to the pubis. Fruit still premature and unripe, that is unsustainable, as a function of its internal organs and systems still not perfect. After the birth of the survival of the fetus is small and is possible only under especially favorable conditions.
In the 34th week, the fetus has a length of about 40 cm, weight - about 1, 6 kg. The fetus is viable, but require special conditions of care.
At 38-40 weeks, the fetus acquires the signs of maturity: its length of 45 cm, weight - about 2, 5 kg. "An old man" kind of lost because of which developed subcutaneous tissue, the skin becomes pink, stomach is a normal place. The fruit becomes completely viable.