A 39-year-old patient is contemplating discontinuing birth control pills in order to conceive. She is concerned about her fertility at this age, and inquiries about when she can anticipate resumption of normal menses. You counsel her that by 3 months after discontinuation of birth control pills, the following proportion of patients will resume normal menses

Although the estimated incidence of post-pill amenorrhea is given as 0.7 to 0.8%, there is no evidence to support the idea that oral contraception causes amenorrhea. Eighty percent of women resume normal periods within 3 months of ceasing use of the pill, and 95 to 98% resume normal ovulation within 1 year. If there were a true relationship between the pill and amenorrhea, an increase would be expected in infertility in the pill-using population. This has not been found. Infertility rates are the same for those who have used the pill and those who have not. Patients who have not resumed normal periods 12 months after stopping use of the pill should be evaluated like any other patients with secondary amenorrhea. Women who have irregular menstrual periods are more likely to develop secondary amenorrhea whether they take the pill or not.