Diminished Plasma 17-Ketosteroid Concentration in Pregnancy.

Abstract

Measurements of plasma 17-ketosteroids by a recently described technique (J. Clin. Endocrinol. and Metab., 13: 941, 1953) were made on normal adults and on pregnant women at term. Adult controls showed a mean value of 61 [plus or minus] 5 [mu]g/100 ml of plasma, with no significant difference between the values for men and for non-pregnant women. Pregnant women at term showed mean plasma values of 18 [plus or minus] 2 [mu]g/100 ml,a significantly lower mean than that of control adults. The low plasma 17-ketosteroid concentrations late in pregnancy, together with the known urine 17-ketosteroid excretion data, suggest a slackening off during pregnancy of 17-ketosteroid produqtion by the maternal adrenal cortex. Since the concentration of 17-ketosteroids in umbilical cord plasma is greater than it is at the same time in maternal plasma the inner cortex of the fetal adrenal and/or the placenta probably take over the production of 17-ketosteroids during the latter part of pregnancy.