Pituitary gonadotropin function during human pregnancy: serum FSH and LH levels before and after LHRH administration

Pituitary gonadotropin reserve was evaluated in 8 normal pregnant women (13-35 weeks gestation) by measuring serum concentrations of FSH and LH (betaLH assay) before and after an IV bolus of 100 mug LHRH. Basal levels of FSH and LH were low or undetectable. LHRH administration failed to stimulate FSH release but did result in a small short-lived rise in LH levels. These findings provide further evidence that pituitary gonadotropin synthesis and release are inhibited during pregnancy.