In a normal menstrual cycle there is regular hormone production and thickening of the lining of the uterus. This cycle prepares the endometrium (uterine lining) for implantation of a developing embryo. If no implantation occurs, the lining sheds, resulting in a menstrual period. There are two phases in the menstrual cycle: the follicular phase and the luteal phase. The follicular phase occurs prior to ovulation and involves thickening of the lining of the uterus. This phase usually lasts 10 to 14 days. The luteal phase is the period of time from ovulation to the onset of menses when the lining of the uterus undergoes stabilization prior to menses. This phase usually lasts 14 days.
Cycles are often irregular during the first 2 years after the onset of menstruation. These early cycles are often anovulatory-there is no ovulation during the menstrual cycle and therefore the luteal phase does not occur properly. Because of this a woman will experience irregular bleeding. As long as the menstrual cycles are no longer than 40 days, no shorter than 21 days, and the duration of bleeding is no longer than 7 days, this is considered normal in a woman.
If irregular bleeding lasts longer than 2 years or the blood flow is excessive, your physician may suggest further evaluation.
Indu S. Anand, MD
Dr. Anand is a former Assistant Professor in the Department of Obstetrics and Gynecology at the University of Tennessee Health Science Center, in Memphis, Tennessee. She now is in private practice in Atlanta, GA.