Menstruation How Your Menstrual Cycle Works The key to getting pregnant is understanding how your monthly ovulation cycle works. Premenstrual Syndrome (PMS) The most popular explanation for PMS is that these symptoms are related to cyclic changes in female sex hormones, pituitary hormones, prostaglandins and certain brain chemicals. Mid-Menstrual Cycle Pain (Mittelschmerz) Mittelschmerz comes from the German words for "middle" and "pain." Amenorrhea Amenorrhea means that a woman of childbearing age fails to menstruate. Dysfunctional Uterine Bleeding Dysfunctional uterine bleeding occurs when the cycle's hormonal signaling gets thrown off. Copyright 2001-2010 Aetna Inc. Web Privacy Statement | Legal Statement | Privacy Notices | Member Disclosure