In vivo and in vitro studies of 15alpha-hydroxyprogesterone in the human placenta

Studies were conducted to determine the fate of 15alpha-hydroxyprogesterone in human placental tissue. Tritiated 15alpha-hydroxyprogesterone was perfused through normal human placentas in situ at the time of Cesarean section and incubated with a 10,000x g microsomal supernate of the placenta in vitro. In both systems the substrate, but no additional metabolites were identified. These findings indicate that 15alpha-hydroxyprogesterone is not metabolized during its passage in the human term placenta, and suggests that because of its fetal origin clinical measurements of 15alpha-hydroxyprogesterone may provide a valuable index to the status of fetal viability.