Women with prolactinoma--effect of pregnancy and lactation on serum prolactin and on tumour growth.

Thirty-five women with prolactinoma have been investigated during 41 pregnancies and 35 lactation periods. Nine of the women had a macroadenoma; 4 of them underwent transsphenoidal microsurgery and one was treated with external pituitary irradiation before pregnancy. All nine were given bromocriptine to induce ovulation. Four women with a microadenoma became pregnant without medical treatment, one shortly after pituitary microsurgery. The other 22 women were treated with bromocriptine only for varying periods before conception. Tumour complications developed in 7 women (20%); 3 had signs of optical nerve compression and 4 showed increased sella volume after pregnancy. All women with tumour complications had been treated with bromocriptine for less than 12 months before conception. Serum prolactin (Prl) was measured every four weeks during pregnancy and after cessation of lactation. In contrast to normal pregnancy, the mean serum Prl did not increase during the second and third trimester of pregnancy in women with pretreatment serum Prl levels above 60 micrograms/l. The lactation period did not have any harmful influence on tumour development. It is concluded that neither pretreatment serum Prl nor radiological changes of the sella turcica can predict tumour development during pregnancy. Treatment with bromocriptine for more than 12 months before conception seems to reduce the risk of tumour progress.