Invasive Blood-Seeking Fetuses in Mammals

In most mammals, the mother’s blood supply remains safely isolated from the foetus. It passes its nutrients to the foetus through a filter, which the mother controls. The mother is a despot: she provides only what she chooses, which makes her largely invulnerable to paternal manipulation during pregnancy. In primates and mice, it’s a different story. Cells from the invading placenta digest their way through the endometrial surface, puncturing the mother’s arteries, swarming inside and ...