Aldosterone and corticosterone in amniotic fluid during various stages of pregnancy.

Concentrations of unconjugated aldosterone and corticosterone were measured in amniotic fluid (AF) at different stages of pregnancy. AT 9-20 weeks gestation the mean AF level of aldosterone was 14.4+/0.7 ng/dl, and of corticosterone 82.9 +/- 6.4 ng/dl. Both showed the same pattern during pregnancy, with a rise in AF levels in the last few weeks. At 28-40 weeks gestation the mean AF aldosterone level was 25.5 +/- 2.0 ng/dl and the mean AF corticosterone was 218.3 +/- 26.6 ng/dl.