Preliminary studies show large amounts of chorionic somatomammotropin (HCS) and pituitary prolactin (PRL) in human amniotic fluid; and that their concentrations vary under pathologic circumstances. A series of experiments have been devised to throw further light on the rate-limiting factors which control amniotic fluid concentrations of the two hormones in derangements of maternal and fetal health using the rhesus monkey as a model: changes in endogenous production of the hormone will be brought about along with studies of the acute injection into two compartments of the two radio-labeled hormone preparations and experiments. Further experiments will study the effects of amniotic lactogenic hormones on distribution of water and electrolytes between mother and fetus.