The process of prenatal development occurs in three main stages. The first two weeks after conception are known as the germinal stage, the third through the eighth week is known as the embryonic period, and the time from the ninth week until birth is known as the fetal period
Within 24 hours after fertilization, the egg that will become the baby rapidly divides into many cells. By the eighth week of pregnancy, the baby will change names from an embryo to a fetus. There are about 40 weeks to a typical pregnancy. These weeks are divided into three trimesters. Learn about your baby’s development throughout each stage of pregnancy.