Prolactinomas during pregnancy

During pregnancy, most prolactinomas remain stable and only require clinical monitoring; however, occasionally they enlarge and cause symptoms. The risk of symptomatic enlargement depends on the size of the prolactinoma before pregnancy. A microprolactinoma or small macroprolactinoma (eg contained within the sella) is unlikely to expand symptomatically, particularly if it has previously been treated with surgery or radiotherapy; the risk is around 3 to 5%. For a large macroprolactinoma, the risk of symptomatic enlargement is much higher—up to 30% if the prolactinoma has not been previously treated with surgery or radiotherapy.

In a woman with a microprolactinoma or small macroprolactinoma who is taking dopamine agonist therapy, stop therapy when pregnancy is confirmed. Although bromocriptine and cabergoline have not been associated with miscarriage or congenital malformations, stopping therapy is reasonable because the risk of prolactinoma enlargement in these patients is small. Quinagolide should not be used during pregnancy or prescribed to any woman planning pregnancy.

If dopamine agonist therapy is stopped, assess the woman regularly throughout pregnancy for signs of prolactinoma enlargement (eg headache, visual disturbance). Serum prolactin concentration does not reliably rise with prolactinoma enlargement, so should not be used for monitoring. Formal assessment of visual fields is recommended each trimester for a woman with a macroprolactinoma, but is not necessary for a woman with a microprolactinoma. Magnetic resonance imaging (MRI) is only recommended if the patient becomes symptomatic. If the patient has evidence of prolactinoma enlargement on MRI, treatment with a dopamine agonist can be restarted. Bromocriptine is preferred during pregnancy; cabergoline is suitable second line (see Dopamine agonist therapy for prolactinoma for doses).

For a woman with a large macroprolactinoma, provide counselling about the high risk of prolactinoma enlargement during pregnancy. Surgical debulking before pregnancy greatly reduces this risk, but can affect fertility. Specialist consultation before pregnancy is necessary. If a woman with a large macroprolactinoma becomes pregnant, use bromocriptine therapy throughout the pregnancy. Surgery or early delivery may be necessary if the prolactinoma does not respond to dopamine agonist therapy.