Endocrine Abstracts

There are two issues: i) dopamine agonist (DA) safety for mother and baby, and ii) risk of oestrogen-induced prolactinoma enlargement. Bromocriptine (BC) and Cabergoline (CAB) are both safe for ovulation induction but the safety database is larger for BC (6239 pregnancies) than for CAB (789). Neither drug causes increases in miscarriage, premature delivery, multiple births or congenital malformations, compared to data for normal pregnancy. Risk of symptomatic tumour enlargement during pregnancy depends on prolactinoma size and its responsiveness to DA therapy before pregnancy. For micro prolactinoma the risk is only 2%. For untreated macro prolactinoma, the risk is ∼20% but the figure is probably ∼10% for DA-responsive tumours treated medically for at least 6 months before conception. DA-induced tumour fibrosis may limit early reexpansion.

Management: For patients with micro prolactinoma, DA can be safely stopped when pregnancy is confirmed. Formal visual fields and serum PRL measurements are unnecessary. Breast feeding can be encouraged and up to one-third of tumours remit after pregnancy. For patients with macro prolactinoma, DA should be used for 6–12 months before conception is attempted. If post-treatment MRI shows intrasellar tumour, DA can be stopped when pregnancy is confirmed; fewer than 10% develop symptomatic enlargement (for which DA therapy can be restarted, usually with BC). If significant extrasellar tumour persists, either debulking surgery before pregnancy or continued DA therapy throughout pregnancy can be considered. The safety data for BC and CAB usage throughout pregnancy are broadly reassuring but experience remains limited. Visual fields should be monitored every 1–3 m and MRI reserved for those with symptoms of tumour enlargement.

Recommended reading: Lebbe M et al, Clin Endocrinol (2010), 73:236 (outcome of 100 cabergoline-initiated pregnancies). Molitch ME. Prolactinoma in pregnancy. Best Pract Res Clin Endocrinol Metab (2011), 25:885 (comprehensive review).