The menstrual cycle is the regular natural change that occurs in the female reproductive system (specifically the uterus and ovaries) that makes pregnancy possible.[1][2] The cycle is required for the production of ovocytes, and for the preparation of the uterus for pregnancy.[1] Up to 80% of women report having some symptoms during the one to two weeks prior to menstruation.[3] Common symptoms include acne, tender breasts, bloating, feeling tired, irritability and mood changes.[4] These symptoms interfere with normal life and therefore qualify as premenstrual syndrome in 20 to 30% of women. In 3 to 8%, they are severe.[3]
