The placenta’s role as a mediating passage between bodies has been a conceptual resource for feminist theorists and philosophers interested in developing more nuanced explanations of the maternal–fetal relation, a relation that has tended to be identified with maternal and fetal bodies rather than with the placenta between them. I draw on efforts by philosopher Luce Irigaray and her readers to theorise placental relations as a model for the negotiation of differences. In her more recent work, Irigaray figures the placenta (...) as an enveloping space of metaphorical enclosure. The placental relation in Irigaray’s work thus offers insights into the temporal structure of her theory of becoming and can inform a more ‘materialist’ account of pregnancy. I then consider how placental relations are conceptual resources for re-imagining relations of self–other in pregnancy, and for addressing emergent ethical concerns over the transformation of the placenta into a scientific object. (shrink)