Is it uncommon for a pregnant woman to get pituitary tumors?

Yes. Pituitary tumors often disrupt hormones and make it difficult to get pregnant. During pregnancy the pituitary gland can enhance on brain scan and look like a tumor. A minor tumor that already is present may get activated during pregnancy. A thorough medical evaluation would be appropriate.
Yes. Yes, pituitary tumors during pregnancy are uncommon. (reference mayo clin proc. Apr 1990;65(4):461-74). The gland does enlarge a bit, but those changes reverse after delivery.

Related Questions

Can I get preganant if I have a pituitary tumor anf my breast is producing milk from it?

Prolactinoma N preg. Small prolactinoma producing little prolactin may not affect your chance of pregnancy, but one that is producing much hormone will likely reduce your chance some what. Many women who are actively breastfeeding produce higher prolactin than nonlactating females, but they still get pregnant during this time. So if u r trying for it, good luck, if trouble, consult doc. Good luck. Read more...
Maybe. You should discuss this with your endocrinologist/ob/gyne before getting pregnant. There are risks to consider, especially that higher estrogen levels during pregnancy may cause further growth of prolactinoma which may affect vision, etc. Read more...