The Menstrual Cycle

The Menstrual Cycle, Days 1 through 28

(1) Days 1–5: Monthly bleeding.  Usually lasts from 2–7 days, often about 5 days. If there is no pregnancy, the thickened lining of the womb is shed. It leaves the body through the vagina. This monthly bleeding is also called menstruation. Contractions of the womb at this time can cause cramps. Some women bleed for a short time (for example, 2 days), while others bleed for up to 8 days. Bleeding can be heavy or light. If the egg is fertilized by a man’s sperm, the woman may become pregnant, and monthly bleeding stops. (2) Day 14: Release of egg. Usually occurs between days 7 and 21 of the cycle, often around day 14. Usually, one of the ovaries releases one egg in each cycle (usually once a month). The egg travels through a fallopian tube towards the womb. It may be fertilized in the tube at this time by a sperm cell that has travelled from the vagina. (3) Days 15–28: Thickening of the womb lining. Usually about 14 days long, after ovulation. The lining of the uterus (endometrium) becomes thicker during this time to prepare for a fertilized egg. Usually there is no pregnancy, and the unfertilized egg cell dissolves in the reproductive tract.