A fetus or foetus is the unborn offspring that develops from a mammal embryo. Following embryonic development, the fetal stage of development takes place. In human prenatal development, fetal development begins from the ninth week after fertilization and continues until the birth of a newborn. Prenatal development is a continuum, with no clear defining feature distinguishing an embryo from a fetus. However, a fetus is characterized by the presence of all the major body organs, though they will not yet be fully developed and functional and some not yet situated in their final anatomical location.

सस्तनी किंवा जरायुज पृष्ठवंशधारी प्राण्यांमधील गर्भधारणा ते जन्म या दरम्यानची अवस्था म्हणजे गर्भ होय.