Women in the developed world reach this last reproductive milestone at around 50 years, on average. (For a variety of genetic and environmental factors, in rural, developing countries the average of age of menopause is earlier: around age 43.) If your mother or grandmother had an early menopause, you’re apt to follow suit. Likewise, if they didn’t stop menstruating until their early to mid-fifties, you may gain a longer stretch of fertile years. But this isn’t cast in stone. A special workshop on Stages of Reproductive Aging, hosted by the National Institutes of Health in 2001, noted that individual women may be born with “a highly variable number of oocytes [eggs]” and that the rate at which they lose eggs also varies greatly. So talk to Mom, but remember, biology isn’t necessarily destiny.