Prolactinoma. A prolactinoma is a tumor of the pituitary gland and part of the hormonal regulation in the human body. If you have a prolactinoma with high secretion of the prolactin this can definitely prevent a pregnancy from occurring. You would need to see an hormone specialist for evaluation and drug treatment or if the lesion is large then a neurosurgeon for possible surgical resection.
Several ways. Sometimes a prolactinoma can prevent a woman from getting pregnant. The gland that produces prolactin normally increases in size during pregnancy. Women with prolactinomas that are already large may have problems with headaches or vision problems if it increases even further during pregnancy. However, most women with prolactinomas do not have any issues in pregnancy.