My dearly departed Daddy Sam Jones taught our weekly bible study/church meetings using Les Feldick's books as a guide. I learned even more by listening to the recorded sessions on Les Feldick's online site and following along in my own bible. Now that's challenging! I thank God for gifting us with Les Feldick. In regards to the comment about fetal blood supply I'd like to post this quote: Does a fetus have its own blood supply?
Small blood vessels carrying the fetal blood run through the placenta, which is full of maternal blood. Nutrients and oxygen from the mother's blood are transferred to the fetal blood, while waste products are transferred from the fetal blood to the maternal blood, without the two blood supplies mixing.