Decrease in serum prolactin during bromocriptine-induced pregnancy and subsequent restoration of reproductive function in some hyperprolactinemic women.

Twenty-two women with hyperprolactinemia and amenorrhea were followed up for at least 18 months after 22 bromocriptine-induced full term pregnancies. Return of menstruation occurred in 9 of the 22 patients after pregnancy. Five of them conceived subsequently without any treatment. The prolactin (PRL) concentration before or during bromocriptine treatment was not significantly different between the patients who conceived spontaneously and those who did not. However, the PRL concentration after weaning was significantly lower in the patients who conceived spontaneously than in those who did not. Serum PRL levels were normal or only slightly elevated in the patients who conceived spontaneously. In 11 of the 22 patients, PRL levels were serially determined during bromocriptine-induced pregnancies. In 7 of the 11 patients, serum PRL levels fell during the second or third trimester. Spontaneous pregnancy occurred in 3 of the 7 patients who showed a decrease in PRL values during pregnancy, but in none of the 4 patients who did not. Furthermore, PRL levels after weaning correlated with PRL levels during the third trimester in these 11 women. Consequently, a decrease in PRL values during pregnancy may result in a fall in PRL levels after pregnancy, which in turn leads to the restoration of reproductive function in some subjects.