Prolactinoma During Pregnancy

Risks of prolactinoma to the mother

The major risk to the mother with has a prolactinoma during pregnancy is an increase in the size of the pituitary tumor leading to vision impairment. During a normal pregnancy, estrogen levels rise which are thought to also normally cause an increase in the size of the prolactin producing cells in the pituitary. This is called lactotroph hyperplasia. In women with prolactinomas, this hyperplasia response can cause the adenoma to increase in size. The worry is that the adenoma can get large enough to push on the nearby optic chiasm and cause vision loss. See pituitary anatomy section. Adenomas less than 1cm in size have a smaller risk of growth than adenomas that are larger than 1cm.

Risks of prolactinoma to the fetus

The medications used to treat prolactinomas prior to conception are bromocriptine and cabergoline. Data from multiple studies have shown that use of bromocriptine during the first month of pregnancy does not harm the fetus, but there is insufficient data for later use in pregnancy. There is less data available about cabergoline but in over 500 pregnancies with the mother taking cabergoline at the time of conception, there was no increased risk of pregnancy loss or fetal malformations (1,2,3).

Treatment during pregnancy

The most important part of treatment of prolactinoma during pregnancy is planning pre-conception. Either bromocriptine or cabergoline is used to reduce adenoma size and prolactin levels prior to conception. Women with macroadenomas are not encouraged to pursue pregnancy until more definitive treatment is done pre-pregnancy. Every patient is different and individualized management is provided by the endocrinologists at Houston Thyroid and Endocrine Specialists.