A woman's menstrual cycle (monthly period) is controlled by changing levels of certain hormones. These hormones travel through the blood. Two hormones, estrogen and progesterone, play a big role in the menstrual cycle. They are produced in the ovaries (where eggs are stored).
Hormones help prepare the uterus for pregnancy. At the start of the cycle, the 2 ovaries produce estrogen. This makes 1 ovary release an egg, and signals the production of progesterone. The egg travels through the fallopian tube. Then it enters the uterus. If the egg is fertilized, a woman becomes pregnant. If this doesn't happen, the egg is shed along with the uterine lining. This bleeding is called menstruation.
Days 1 to 7
Days 8 to 14
Increased and thickened vaginal mucus
Days 15 to 28