[Plasma aldosterone in pregnancy, during labor and in the newborn infant].

Plasma aldosterone levels of mother and child during pregnancy were measured by means of radio-immuno assay without chromatography. In cases of unconspicuous pregnancy average aldosterone concentrations were found to increase from 23.2 ng/100 ml in the first trimester to 37.2 ng/100 ml in the second trimester and further to 64.0 ng/100 ml in the third.--High values were recorded from mothers (71.9 ng/100 ml) after birth and from umbilical cord blood of vaginally delivered newborns (83.4 ng/100 ml).--Aldosterone values as low as 60.9 ng/100 ml were recorded from newborns delivered by caesarean section with reduced parturitional stress. These were lower with significance than the levels recordable from newborns after spontaneous vaginal delivery (83.4 ng/100 ml). Values lower with significance were recorded from plasma of pre-eclamptic women in the third trimester (41.9 ng/100 ml).--No difference was found to exist between aldosterone concentrations in umbilico-arterial blood, on the one hand, and those in umbilico-venous blood, on the other.