Cyclic 3',5' -adenosine monophosphate in umbilical cord and maternal plasma before and after the onset of parturition.

Significant arteriovenous differences in cord cyclic 3',5'-adenosine monophosphate (cAMP) levels and between the maternal plasma (MP) and each cord vessel (mean umbilical artery [UA] greater than umbilical vein [UV] greater than MP) was observed. cAMP levels were significantly higher in the umbilical cord vessels and maternal plasma after vaginal delivery than they were following delivery by elective cesarean section before the onset of labor. The higher mean cAMP levels observed after parturition appeared to be more pronounced in the fetoplacental unit than in the maternal compartment. A significant positive correlation in cAMP levels between the UA and UV was also observed.