Exclusion of the fetal brain as the main source of rat and human amniotic fluid oxytocin

Summary. At term relatively high oxytocin concentrations are found in maternal plasma and in rat and human amniotic fluid. To determine the contribution of the fetal brain to these oxytocin levels, the peptide was measured in maternal rat plasma and amniotic fluid 2 days after intrauterine removal of the fetal brains, and in the amniotic fluid of 16 human anencephalics. After removal of the fetal rat brains and in human anencephalic pregnancies normal maternal plasma concentrations and amniotic fluid oxytocin contents were found. Consequently, both maternal plasma oxytocin and amniotic fluid oxytocin are not determined to any substantial degree by the fetal brain.