The fertilized egg cell develops into a multicellular embryo when it begins dividing. At the beginning, the embryo is only a couple of millimetres in size. The embryo attaches itself into the mucous membrane of the mother's womb. There, its cells continue dividing. 

Gradually, the parts of the embryo begin to differentiate. This means that the embryo begins to develop distinct organs. When an embryo reaches the age of approximately two months, it will be a couple of centimetres in length and recognizable as a human. When this happens, the embryo is considered a fetus. 

The fetus develops in the mother's womb protected by amniotic fluid. The fetus needs oxygen and food in order to survive and continue growing. The fetus receives these things from its mother through the umbilical cord. The carbon dioxide and urea produced by the fetus are also released through the umbilical cord.

The organs and senses of the fetus develop rapidly. The fetus learns to recognize persons that are speaking around its mother, and it is capable of kicking.