History of placental studies.
D036861:Delivery, Obstetric / Q000379:methods; D049668:History, 15th Century; D049669:History, 16th Century; D049670:History, 17th Century; D049671:History, 18th Century; D049672:History, 19th Century; D049673:History, 20th Century; D049690:History, Ancient; D009774:Obstetrics / Q000266:history*; D010920:Placenta / Q000033:anatomy & histology / Q000502:physiology*