In school, whether it is in sex education or in biology, we are taught about the normal woman’s reproductive system. We are taught that the normal woman’s menstrual cycle is around 28 days. We are taught she has regular predictable periods. We are taught that in a normal woman these periods are 5 days in length and start at age 12 or 13. Our doctors and our politicians grow up ascribing to this idea of the normal woman. However what we are never taught is that she does not exist. Calling the reproductive biology of any woman ‘normal’ is misleading when the existent natural variation both is huge and critically under acknowledged in education and medical practice. Ignoring this variation could well be leading to unnecessarily high levels of side effects from hormonal contraception and certainly leading to young girls thinking their bodies’ reactions may be abnormal or dysfunctional. We need to appreciate and account for this diversity when planning sexual health policy and education.