Plasma Steroid Concentrations in Maternal and Umbilical Circulation after Spontaneous Onset of Labor*

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Abstract
Blood samples were obtained from the maternal peripheral vein (n = 17) during the second stage of spontaneous labor and from the umbilical artery (UA) and vein (UVn) immediately after delivery. Four Δ4-and five Δ5-steroids as well as estradiol were measured by RIA. Additionally, cortisol was determined in maternal plasma. The maternal concentrations were compared with our control values obtained from samples (n = 30) collected at term but not in labor. All Δ5-steroids and F were significantly higher during labor than before labor. In the umbilical circulation, progesterone and 17-hydroxyprogesterone were significantly higher in the UVn than in UA (P < 0.05). Whereas androstenedione was significantly higher in the UA [1.01 ± 0.12 ng/ml (mean ± SEM)] than in the UVn (0.72 ± 0.07 ng/ml), testosterone was almost identical in the two (UA, 0.33 ± 0.03 hg/ml; UVn, 0.35 ± 0.08 ng/ml). Four of the five A5- steroids (dehydroepiandrosterone, dehydroepiandrosterone sulfate, pregnenolone sulfate, and 17-hydroxypregnenolone) had significantly higher concentrations in the UA than in the UVn (P < 0.05). However, pregnenolone levels were not significantly different (UVn, 21.8 ± 2.0 ng/ml; UA, 18.0 ± 2.0 ng/ml). No significant correlations were observed between maternal and umbilical steroid concentrations.