Circulating neurohypophyseal hormones in anencephalic infants.

Human anencephalic infants have always been considered not to have circulating levels of oxytocin or vasopressin. However, this article shows that amniotic oxytocin levels in anencephalic infants without hydramnios fall within the control range. In addition, low levels of both oxytocin and vasopressin are present in the umbilical circulation. These peptides are probably derived from fetal sources other than the fetal brain, for example, the fetal adrenal cortex.