Menstrual Cycle Irregularity and Premature Death: The Take-Home Message

JoAnn E. Manson, MD, DrPH


November 05, 2020

This transcript has been edited for clarity.

Hello. This is Dr JoAnn Manson, professor of medicine at Harvard Medical School and Brigham and Women's Hospital.

I'd like to talk with you about a recent report in The BMJ on menstrual cycle regularity and length during the early and middle reproductive years, as well as the risk for premature death from cardiovascular disease, cancer, and all causes. I'd like to acknowledge that I'm a coauthor of this report.

We've known for a long time that irregular menstrual cycles can be a marker for polycystic ovarian syndrome, increased risk for type 2 diabetes, and even cardiovascular disease. This, however, is the most detailed and comprehensive report on the association with premature death (death before age 70) and cause-specific mortality.

The cohort was the Nurses Health Study II, about 80,000 US women who were age 25-42 at enrollment and who were followed for about 24 years. These women reported their menstrual cycle characteristics during adolescence, early adulthood, and the middle reproductive years.

Compared with women who reported regular menstrual cycles that averaged 26-31 days (varying by no more than 4 days), the women who reported always having irregular menstrual cycles or cycles that tended to last 40 days or longer had an increased risk for premature death before age 70, as well as an increased risk for cardiovascular and cancer death. These women averaged a 30%-40% increased risk for all-cause mortality, with the greatest increase seen in cardiovascular death. Women with irregular cycles during the middle reproductive years had up to a 60% increase in risk for cardiovascular death.

Women taking oral contraceptives were analyzed separately, so that was not a confounder of these associations. We also adjusted for body mass index, physical activity, and other lifestyle factors so that it appeared that irregular or long menstrual cycles were an independent marker of increased risk for premature mortality.

Why would this be the case? We know that regular menstrual cycles indicate a generally healthy hypothalamic-pituitary-ovarian access. We also know that hormonal and metabolic perturbations or disruptions can lead to irregular menstrual cycles.

All of this suggests the value of asking women about the regularity of their menstrual cycles and the average length, which might be markers for general health. Try to determine the underlying cause for those women who report irregular or excessively long menstrual cycles. These questions may also help to identify women who can be targeted for more diligent control of their risk factors, such as hypertension and dyslipidemia, with a focus on lifestyle modification, including increased physical activity and a heart-healthy diet.

Thank you so much for your attention. This is JoAnn Manson.

Dr JoAnn Manson is a professor of medicine at Harvard Medical School and chief of the Division of Preventive Medicine at Brigham and Women's Hospital in Boston, Massachusetts.

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