Interrelationships between maternal and cord prolactin, progesterone, estradiol, 13,14-dihydro-15-keto-prostaglandin F2alpha, and cord cortisol at delivery with respect to initiation of parturition.

Estradiol, progesterone, prolactin, and 13,14-dihydro-15-keto prostaglandin F2alpha (PGFM) were measured in both maternal and cord venous blood obtained at the time of delivery in 24 maternal infant pairs evenly divided among six different physiologic groups. Progesterone and prolactin were significantly higher and estradiol was significantly lower in cord than in maternal blood. There were no significant differences between the groups for cortisol, estradiol, or progesterone in maternal or cord blood. A significant increase in prolactin was demonstrated in women receiving oxytocin for induction of labor. Both estradiol and PGFM were highly correlated between maternal and cord blood. PGFM was significantly higher in cesarean section patients in labor than in those not in labor in both the maternal and cord circulations. Among those delivered vaginally, PGFM tended to be higher in those in spontaneous labor than in those with induced labor. PGFM in induced labor was intermediate between spontaneous labor aptients delivered by cesarean section and those delivered vaginally. Duration of labor was negatively correlated with cord estradiol concentration. The physiologic significance of these findings is discussed.