Hormonal response to exogenous luteinizing hormone-releasing hormone and thyrotropin-releasing hormone in pregnancy and puerperium.

Luteinizing hormone-releasing hormone (LH-RH) and thyrotropin-releasing hormone (TRH) were injected into five women in the last month of pregnancy and three women in the postpartum period. In seven of the women, follicle-stimualating hormone (FSH) levels were at the limit of sensitivity of the assay and there was no response to LH-RH. One postpartum subject tested three weeks after delivery did show an FSH response to LH-RH. The thyrotropin response to TRH was within normal limits. When compared with control subjects, the pregnant and puerperal women had elevated basal levels of prolactin and an exaggerated response to TRH. Growth hormone levels were low and there was an inconsistent response to the administration of the releasing hormones. These results indicate that in pregnancy the thyrotroph and lactotroph are responsive to stimulation, whereas the gonadotroph is suppressed.