The average duration of pregnancy is 280 days. For these days in the woman's womb there is a real miracle - the development of the human embryo.
Stages of embryo development
1-4 weeks. The process of development of the embryo begins immediately after the fertilization of the egg - instantly begins active division of cells. Already in this period, the future baby is laid all vital organs, and by the end of the fourth week in it begins to circulate blood. The size of the embryo is no more than a grain of sand.
5-8 weeks. The embryo at 5 weeks already eats not from the fetal egg, but from the mother's body, since it has a developed umbilical cord and implanted into the wall of the uterus. At this stage, the main stages of embryo development take place, the most important external structures are actively forming - the head, arms and legs, eye sockets, the rudiments of the nose, and the mouth form. The baby starts to move.
9-12 weeks. At this time, the embryonic development of the embryo ends. Further, the embryo will have the obstetrical name "fetus". The human embryo is already fully formed by 12 weeks, all of its systems are completely ready and will only continue to develop.
13-24 weeks. Formation of the embryo during the second trimester includes such changes: the cartilage of the skeleton turns into bones, hair appears on the skin of the head and face, the ears take their right position, nails are formed, grooves on the heels and palms (the basis for future prints). The child hears sounds at the 18th week, at the 19th week the formation of subcutaneous fat begins. The embryo has genitals for 20 weeks. At the 24th week, the viability of the unborn child is launched - the surfactant begins to be produced in the lungs, which does not allow the capillary sacs to close during respiration.
25-36 weeks. In the tongue of the baby, taste buds are formed, all organs continue to develop, the brain rapidly grows and develops. For the first time in the 28th week, the baby opens his eyes. Active development of subcutaneous fat, which by the 36th week is 8% of the total mass.
37-40 weeks. The child takes the position in which he will be born. From now on, he is ready for life in the external environment.
Dimensions of the embryo by week:
- 12 weeks - growth of the child approximately 61 mm, its weight - 14 g;
- 16 weeks - 12 cm, 130 g;
- 20 weeks - 16 cm, 320 g;
- 24 weeks - 21 cm, 630 g;
- 28 weeks - 35 cm, 1 kg;
- 32 weeks - 40-41 cm, 1600 g;
- 37-40 weeks - 45 cm, 2500 g;
A full-term child is born on average with an increase of 51 cm and weight - 3400 g.