Serum estradiol 17-sulphate and lipid peroxides in late pregnancy.

Estradiol 17-sulphate is readily converted to 2-OH or 4-OH estradiol 17-sulphate. The latter two strongly antagonize lipid peroxidation, which may play certain roles during pregnancy, such as pregnancy-induced hypertension. Serum estradiol 17-sulphate during mid and late pregnancy was measured using a direct radioimmunoassay without hydrolysis, and the level increased as pregnancy progressed. The levels in the sixth (20-23 weeks) and tenth months (36-39 weeks) of gestation were 1.42 +/- 0.04 nmol/l (mean +/- SD) and 3.42 +/- 1.09 nmol/l, respectively. The maternal venous levels before and at delivery and in the umbilical veins and artery were 3.38 +/- 0.83, 3.48 +/- 1.53, 4.11 +/- 1.40 and 4.30 +/- 1.81 nmol/l, respectively. The latter two values were slightly higher than the former two. Estradiol 17-sulphate in maternal venous blood began to decrease around delivery. Serum lipid peroxides were measured using the method of Yagi. Estradiol 17-sulphate and lipid peroxides showed a simple regression slope (r = -0.548, p less than 0.05) during late pregnancy. These results suggest that estradiol 17-sulphate may be converted to 2-OH or 4-OH estradiol 17-sulphate, which act as lipid peroxide scavengers during pregnancy.