A hormone secreted by the pituitary gland. Its major role is to control milk production. Excess secretion can interfere with normal ovulation. This is why prolactin levels are checked in every woman during the infertility evaluation process. Certain women have elevated Prolactin levels due to a small benign tumor in the pituitary gland or the brain. These tumors are often called Prolactinomas. They are usually treated by a medication called Bromocriptine or Parlodel. In rare instances, surgery may be required.