Surveillance of pituitary tumours in pregnancy

Summary

Women with functioning anterior pituitary disease are often anovulatory. Once the condition is treated with medication or surgery, women are able to ovulate and conceive. This can occur before their first normal menstruation, so unless adequate contraception is used, they will conceive whilst still on medical treatment. Therefore the fetus may be exposed to dopamine agonists at an early stage in development. With the exception of macroprolactinoma there is limited knowledge about the maternal and fetal consequences of pituitary tumours and the drugs used to treat them in pregnancy.

The pituitary increases in size in all pregnancies, if there is an underlying adenoma, the normal growth in addition to an abnormal pituitary can have serious consequences if not diagnosed early and treated appropriately. As the disease is rare the only information we have so far is based on case studies. UKOSS gives us the opportunity to collect some much needed data on these conditions in pregnancy and the effect on the mother and fetus. We know from case reports that Cushing's disease and acromegaly can have devastating consequences including fetal and maternal mortality and serious morbidity. Macroprolactinomas and non-functioning tumours may enlarge, thereby threatening vision and necessitating surgery.

Of 119 cases notified to UKOSS, 71 met the case definitions: 49 macroprolactinoma; 16 non-functioning pituitary tumours; 3 acromegaly and 3 Cushing’s disease (thus 6 GH and ACTH-secreting tumours). Hence these tumours are all rare with an incidence of 1.8 macroprolactinomas per 100,000 pregnancies (95% CI 1.3-2.4), 0.6 non-functioning pituitary tumours per 100,000 (95% CI 0.3-1.0), and 0.1 GH and ACTH secreting tumours per 100,000 (95% CI 0.02-0.3). All pituitary tumours in pregnancy are thus rare; however, non-functioning pituitary tumours are more common than previously thought.