The research: Between 1959 and 1967, researchers from the Public Health Institute in Berkeley, CA enrolled more than 14,000 pregnant women and tracked their health for the next 50 years. They found that women with irregular menstrual cycles (defined as an unpredictable cycle, a cycle that regularly varies in length by more than 10 days, or a cycle that’s regularly longer than 35 days) had a 2.4-fold increased risk of death due to ovarian cancer. The researchers can’t say for sure why there seems to be a such a strong correlation between irregular cycles and incidence of ovarian cancer, but the news does come as a surprise, since it was previously thought that less frequent ovulation would protect against ovarian cancer. The researchers also note that their findings don’t apply to women going through perimenopause, when menstrual cycle fluctuations are to be expected. What it means: Irregular periods could be a new risk factor for ovarian cancer, but that doesn’t mean that women with a less-than-precise cycle should be worried. “The lifetime risk for ovarian cancer is about 1 in 71,” says Barbara Cohn, PhD, lead researcher and director of Child Health and Development Studies at the Public Health Institute. “That’s relatively small, and two times a small risk is still a small risk.” Especially compared to other health concerns like breast cancer, where the lifetime risk for women is 1 in 8. The bottom line: If you’re not already familiar with your cycle, start there. Keep tabs on it every month (try an app like Period Tracker), and if you find that you meet the criteria of irregular menstrual cycles, talk to your doctor. She may recommend oral contraception to help regularize your cycle; research shows that the pill is linked to a lower incidence of ovarian cancer. More from Prevention: Your Menstrual Cycle: How Hormones Affect Your Health
