[Hypothalamic-pituitary function in women after abortion or premature labor]

Hypothalamic function during pregnancy and hypothalamic-pituitary function during the first month after abortion or premature labor have been studied. The plasma LH-RH level in pregnant women was significantly lower between 18 and 23 weeks' gestation than that in eumenorrheic women on day 8 or 9 of the normal cycle, and thereafter decreased until term. Serum FSH showed normal response to LH-RH on day 10 after pregnancy termination between 5 and 23 weeks' gestation, but no FSH response to LH-RH was found on day 10 after premature labor at 33 weeks' gestation. Serum FSH responded normally to LH-RH on day 30 after pregnancy termination at 18 weeks' gestation, but serum FSH responded excessively to LH-RH on day 30 after premature labor at 30 weeks' gestation. The positive feedback effect of estrogen on LH release was not operative on day 30 after pregnancy termination beyond 18 weeks' gestation, though it was operative on day 30 after pregnancy termination between 6 and 11 weeks' gestation. These results indicate that the duration of pregnancy has an influence on the recovery of hypothalamic-pituitary function after pregnancy termination and that the recovery of hypothalamic-pituitary function during the first month after premature labor beyond 30 weeks' gestation is similar to that after normal labor.