Prenatal or antenatal development is the process in which a human embryo and later fetus (or foetus) develops during pregnancy, from fertilization until birth. Often, the terms fetal development, or embryology are used in a similar sense.

After fertilization, the process of embryogenesis (the early stages of prenatal development) begins. By the end of the tenth week of gestational age the embryo has acquired its basic form and the next period is that of fetal development where the organs become fully developed. This fetal period is described both topically (by organ) and chronologically (by time) with major occurrences being listed by gestational age.