Maternal peripheral concentrations of estradiol, estrone, cortisol, and progesterone during late pregnancy in rhesus monkeys (Macaca mulatta) and after experimental fetal anencephaly and fetal death

Abstract

Estradiol, estrone, cortisol, and progesterone were measured serially in maternal venous plasma during late pregnancy in four intact rhesus monkeys (Macsca mulatta) and in six monkeys with experimental anencephaHc fetuses (functionally hypophysectomized fetuses). Estradiol and estrone increased gradually and significantly (P <0.05) during the 2 weeks preceding spontaneous vaginal delivery in normal monkeys. Progesterone did not decrease prior to parturition. Cortisol increased sharply on the day of delivery, whereas estradiol, estrone, and progesterone decreased precipitously. In mothers with live, anencephalic fetuses, estradiol was significantly lower than in normal monkeys during late gestation (P <0.05); however, estrone, cortisol, and progesterone values were not different from those in control monkeys. Fetal death occurred in three monkeys at various times after experimental fetal anencephaly and resulted in substantial decreases in maternal estradiol and estrone. Cortisol and progesterone were not affected. Spontaneous vaginal delivery occurred in two animals; pregnancy was substantially prolonged in four. Vaginal delivery was induced by administering estradiol benzoate to a monkey with prolonged pregnancy and a dead fetus. These data suggest that estrogens are involved in the onset of parturition in primates and that a live fetus with an intact hypothalamic-pituitary-adrenal axis is essential for normal concentrations of maternal estrogens but not cortisol or progesterone.