Elevation of dopamine in fetal plasma and the amniotic fluid during gestation.

Catecholamines were determined by a radioenzymatic assay in maternal and fetal rat plasma and in the amniotic fluid during the last five days of gestation. Dopamine was significantly higher in fetal than in maternal plasma whereas norepinephrine was the same. Epinephrine was sighificantly lower in fetal than in maternal plasma on days 18 and 19, but was the same during the remainder of gestation. Dopamine was the predominant catecholamine in the amniotic fluid on days 20-22 of gestation showing the largest percent increase prior to parturition. The data suggest that dopamine may have a peripheral hormonal role during fetal development and parturition.