SOURCES OF 17-ALPHA-HYDROXYPREGNENOLONE AND ITS SULFATE IN HUMAN PREGNANCY

Sources of 17a-hydroxypregnenolone (17-0H-A5P) and its sulfate in human pregnancy were studied by measuring their concentrations in maternal venous plasma (MPV) and amniotic fluid (AF) of patients at midpregnancy, and in the AF, MPV, retroplacental space (RPS), umbilical cord artery (UA), and vein (UV) plasma of patients at term. The MPV concentrations (mean ± SE, nanograms per ml) of 17-OH-Δ5P (and its sulfate) of 0.8 ± 0.2 (1.8 ± 0.5) observed in the nonpregnant state were not different from those of 0.9 ±0.1 (2.4 ± 0.5) and 1.2 ± 0.2 (2.1 ± 0.4) seen at mid-and term gestation, respectively. Delivery induced a 2 to 3-fold rise in the MPV concentrations of 17-OH-Δ5P (and its sulfate; P < 0.05) with the following results (mean ± SE, nanograms per ml): MPV, 3.2 ± 0.7 (4.2 ± 0.6); RPS, 2.5 ± 0.6 (5.8 ± 1.2); UA, 18.5 ± 4.4 (789.4 ± 114.0); UV, 3.2 ± 0.5 (802.2 ± 101.9). At midpregnancy, the concentration of 17-OH-Δ5P (mean ± SE, nanograms per ml) in AF of 1.5 ± 0.3 was 2-fold higher than at term (0.8 ± 0.1; P < 0.05), whereas the respective concentrations of 17-OH-AnP sulfate were similar (2.0 ± 0.2 vs. 3.6 ± 0.7). Dexamethasone administered to five patients 8-10 h before elective cesarean section significantly (P < 0.05) suppressed the concentrations of 17-OH-Δ5P and its sulfate in MPV, UA, and UV, whereas in AF, only the unconjugated form was decreased. In nine patients bearing anencephalic fetuses, the concentrations of both steroids in MPV were normal, whereas those in amniotic fluid and UV were mostly subnormal. At term pregnancy, the maternal adrenals provide the bulk of MPV 17-OH-Δ5P and its sulfate, whereas the fetal adrenals are the main source of these steroids in the fetal circulation and in amniotic fluid. © 1978 by The Endocrine Society.