Females of reproductive age experience hormonal cycles. These cycles repeat over an interval of one month. With every menstrual cycle, a woman's body prepares for a potential pregnancy, with or without the woman's intention. The term menstruation refers to the periodic shedding of the endometrium lining. The average menstrual cycle which takes about 28 days occurs in three phases: the follicular phase, the ovulatory phase (ovulation), and the luteal phase.