Pregnancy averages about 280 days. During this period, a small fertilized egg increases in size, constantly divides into segments, from which organs and systems develop in the future. The organ systems at different stages of development of the human embryo undergo constant changes, and eventually the child becomes capable of life outside the mother's body. But a long nine months must pass before the human embryo becomes viable for the external environment.
Before the embryo begins to develop, fertilization of the egg must occur. For this, a follicle must mature, from which a suitable fetal egg will come out. During this period, called ovulation, fertilization should occur. Only then does the gradual development of a new person begin. The stages of development of a human embryo are rather arbitrary, in fact, development occurs every second for nine months, but doctors conditionally divided pregnancy into trimesters, each of which has its own cycle of development.
Development stages1month (1-4 weeks). The entire period is a constant cell division of the fetal egg and its increase in size. From the cells, internal organs are laid, and at the end of the period, blood circulation begins. The human fetus at this stage is the size of a grain of sand.
2 month (5-8 weeks). The umbilical cord develops and the formation of external organs and segmentation of the body into arms, legs, head. The baby's face begins to show.
3 month (9-12 weeks). The embryo begins to move. The embryonic period is coming to an end, the first trimester is coming to an end. From that moment on, it can be called the human embryo. He already has all the organ systems that will only develop in the future. It is now possible to identify only the head section, the tail section and the kidneys of the arms and legs, from which the limbs will develop in the future.
Month 4 (weeks 13-17). The second trimester begins. The face looks more and more like a human: the ears fall into place, the eyes continue to be closed. The limbs are already quite developed, but the fingers are still in their infancy.
5 month (18-21 weeks). The cartilaginous skeleton gradually hardens, bones develop. The fetus begins to hear sounds, and subcutaneous fat begins to accumulate in it. The hands and feet are developing, the baby has fully developed limbs.
6 month (22-26 weeks). The skin begins to function, hair appears on the head and face, nails form. The genitals, which are already developed, are clearly visible. The human fetus becomes viable.
Month 7 (weeks 27-31). Baby canopen your eyes. Now he is very mobile and mom can feel it. His hair is growing fast and he is gaining weight. All organs continue to develop, but he is already ready for life in the outside world.
8 month (32-36 weeks). The brain is actively developing, the stage of formation is being completed. The nervous system becomes complete and fully functional. Gradually, receptors are formed on the tongue. Subcutaneous fat at this stage averages about 8 percent of body weight.
9 month (37-40 weeks). The baby is in the final position for the upcoming birth. Now he is ready and could be born any minute.
