Fetal adrenocorticotropic hormone and prolactin at delivery.

The concentrations of adrenocorticotropic hormone (ACTH) and prolactin in fetal scalp and umbilical cord blood were measured in 49 full-term fetuses, 25 of whom were delivered spontaneously, 10 of whom underwent induced vaginal delivery, and 14 of whom underwent elective cesarean section. Serial fetal scalp blood samples taken during the 35 vaginal deliveries showed no change in concentration of these hormones. The mean (+/- SD) plasma level of ACTH in cord artery blood after vaginal delivery (315 +/- 249 ng/liter) was significantly higher (P less than .05) than after cesarean section (184 +/- 201 ng/liter), indicating that the fetal anterior pituitary is capable of responding to partal stress.