Menstrual flow

Menstrual flow

The menstrual cycle is the series of changes the body goes through to prepare for a pregnancy. About once a month, the lining of the uterus (endometrium) thickens. Then an ovary releases an egg. If the egg is fertilized by sperm and attaches to the lining of the uterus (implants), pregnancy begins. If the egg isn't fertilized or a fertilized egg doesn't implant, the lining of the uterus is shed. This is the monthly menstrual bleeding (also called menstrual period) that happens from the early teen years until menopause, around age 50.

Current as of: November 27, 2023

Author: Healthwise Staff
Clinical Review Board
All Healthwise education is reviewed by a team that includes physicians, nurses, advanced practitioners, registered dieticians, and other healthcare professionals.

This information does not replace the advice of a doctor. Healthwise, Incorporated, disclaims any warranty or liability for your use of this information. Your use of this information means that you agree to the Terms of Use. Learn how we develop our content.