I'd be pretty curious about the mechanism for such transfer. The umbilical cord doesn't contain nerves AFAIK (and even if it did, the whole point of placental

I'd be pretty curious about the mechanism for such transfer. The umbilical cord doesn't contain nerves AFAIK (and even if it did, the whole point of placental reproduction is to isolate the embryo/fetus from the mother, so probably no nervous connection there, either), so that'd preclude a direct connection between their nervous systems. Maybe hormones or some other chemical means?