<P> Prenatal development is the process in which an embryo and later fetus develops during gestation . Prenatal development starts with fertilization the first stage in embryogenesis which continues in fetal development until birth . </P> <P> In human pregnancy, prenatal development, also known as antenatal development, is the development of the embryo following fertilization, and continued as fetal development . By the end of the tenth week of gestational age the embryo has acquired its basic form and is referred to as a fetus . The next period is that of fetal development where many 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 . </P>

Period from fertilization of the ovum to birth