Puerperal lactation, gonadotropin release and estradiol release: effects of metergoline and bromocriptine

The exact cause of amenorrhea during the puerperium is still a matter of debate. PRL might inhibit primarily the release of FSH and LH or their stimulating effects on the ovary. In the study presented here, 28 healthy women were investigated, 13 of them lactating puerperae. In the other 15, lactation was prevented by drugs (metergoline in 9, bromocriptine in 6). The women's serum PRL, FSH, LH, beta-HCG and 17 beta-estradiol as well as their FSH and LH response to LHRH (100 micrograms i.v.) were tested 1, 3, 7 and 14 days after vaginal delivery. Serum PRL levels remained elevated in the lactating puerperae and dropped in the puerperae treated with metergoline or bromocriptine. The pattern of FSH, LH and beta-HCG levels as well as the FSH and LH response to LHRH were superimposable in lactating and in nonlactating women. 17 beta-estradiol levels dropped in all puerperae from day 1 to 7, but rose from day 7 to 14 only in the puerperae treated with metergoline or bromocriptine and not in the lactating women. These data indicate that PRL directly affects the ovarian response to FSH and LH, whereas the release of FSH and LH remains unaffected. A stimulatory effect of metergoline and bromocriptine on the ovarian steroidogenesis cannot be excluded.