This chapter will consider the ongoing metaphysical debate about the nature of pregnancy: is the fetus a part of its gestational carrier, or is it a separate entity merely contained within her? This question has garnered serious metaphysical attention in the last decade to query the many implicit assumptions which have been made about pregnancy and the maternal-fetal relation, and which have shaped (at least in the western world) our socio-cultural, medical, and legal understandings of pregnancy. The debate often focusses on “parthood” versus “container” understandings of pregnancy, both of which will be outlined below, along with suggestions of potential alternative to this dichotomy. Research into the metaphysics of pregnancy is very much ongoing, so this chapter seeks to lay out the debate in its current stage.