[Restoration of pituitary-ovarian function by pulsatile administration of GnRH during the early puerperium]

In general, the hypogonadotropic hypogonadism seen during early puerperium is thought to be due to long-term deprivation of endogenous GnRH during the course of pregnancy. Recently, based on the pulsatile nature of hypothalamic GnRH section, it has been demonstrated that pulsatile administration of this decapeptide is effective in activation of the pituitary-ovarian function and induction of ovulation in patients with endogenous GnRH deficiency. Thus, we investigated whether this physiological replacement of GnRH can bring about the rapid restoration of the pituitary-ovarian function in early puerperal women. Fourteen postpartum women who had undergone cesarean section for obstetric reasons at 37-41 weeks of gestation volunteered for this study. Six of them received 10 micrograms (one subject received 5 micrograms) of GnRH in every 90 min from day 0-5 postpartum for 7-17 days duration by a portable auto-infusion pump. The remaining 8 subjects without treatment served as controls. On day 14 postpartum, serum baseline values of LH and FSH were significantly higher and their responses to the 100 micrograms GnRH challenge test were significantly greater in GnRH-treated subjects than those in the control subjects, respectively. Serum estradiol levels increased day by day, reaching more than 500 pg/ml at the end of the treatment in the 6 subjects. One of them ovulated within 3 weeks postpartum following GnRH treatment and subsequent hCG administration. These results demonstrate that the physiological replacement of pulsatile GnRH can restore the pituitary-ovarian function even within the first 2 weeks postpartum and in the presence of puerperal hyperprolactinemia. They also suggest that a deficiency of endogenous GnRH secretion may account for, at least in part, the pathophysiology of the hypogonadotropic hypogonadism during early puerperium.