Transition from fetal to neonatal circulation William Harvey (1653) had determined that the purpose of the heart was to pump blood throughout the body -- before the discovery of oxygen, .  He further found that if a women died during childbirth, her child was still alive if pulsations of the umbilical cord continued. Charles White (1773) recognized the radical changes in circulation required for transition from fetal to neonatal life, and that fetal shunts in the heart, the foramen ovale and ductus arteriosus must fully constrict before blood flow to the infant's lungs is sufficient for respiration without further support from the placenta. Transition from placental to pulmonary respiration Erasmus Darwin (1796) pointed out that the placenta is the respiratory organ of the fetus, and that oxygen was more frequently needed by the fetus than delivery of any other nutrient  --  oxygen is the most urgent ongoing need of all species dependent upon aerobic metabolism. Postnatal transfer of blood from the placenta to the lungs Budin (1875) and Schücking (1877) measured the blood left behind in the placenta when the cord was ligated before the transition from fetal to neonatal circulation had completed -- with cessation of pulsation in the cord.  Schücking commented that placental blood was intended to fill the pulmonary vessels.   Transition from fetal to neonatal life is not instantaneous, and is not complete until all respiratory function has been taken over by the lungs.  (more research from the 19th century is available, mostly in French and German). Why are these historic findings not understood by present-day specialists in obstetrics and neonatology?  What evidence can they provide that preventing the transfer of blood from placenta to lungs does no harm?