You might be confusing the placenta with the amniotic sac. The placenta is ultimately the part of the embryo that embeds itself in the uterus and triggers the m

You might be confusing the placenta with the amniotic sac. The placenta is ultimately the part of the embryo that embeds itself in the uterus and triggers the mother's pregnancy. It connects to the fetus via the umbilical cord. In practice people don't think of them belonging to the fetus though, and the title "Microplastics found in human placentas" would have been clearer.