Are Irregular Periods a Sign of Menopause?

In your recent post about longevity and menopause, you say that irregular periods before 45 could be an indicator of early menopause. But if 45 is an actual normal age for natural menopause, wouldn’t irregular periods (a sign of perimenopause that can start up to 10 years before) be normal well before 45?

For instance, I seem to be following in my mother’s footsteps. We both had some irregular periods starting at 44, maybe sooner, but she went through full menopause in her mid-50s. So irregular periods as a sign of fluctuating hormones isn’t necessarily a direct indicator of being a stone’s throw from actual menopause, right?

—Liz

Yes and no. What I mean is, not all menstrual irregularity is created equal. Irregular periods are periods that vary by more than seven days from the first day of one period to the first day of the next. But there can be a lot of variability in what exactly that looks like. You could have a 21-day cycle followed by a 36-day cycle followed by a 27-day cycle, and that would be irregular. You could also have a 65-day cycle, then a 30-day cycle, then a 92-day cycle, and that would also be an irregular period.

We know from the data that these two types of irregularity are not the same in what they portend for your future reproductive life. In fact, assuming that the cause of those irregular periods was perimenopause, the first pattern would be considered early perimenopause and the second pattern would be considered late perimenopause.

The authors of the STRAW + 10 report note that early perimenopause can be quite variable in length. Data from the Seattle Midlife Women’s Health Study shows that nearly half of women will move back and forth between the late-reproductive stage and early perimenopause. But once a woman has gone 60 days without a menstrual period due to perimenopause, she is likely to have her last menstrual period in the next one to three years. That means if you are having cycles that are more than 60 days long between the ages of 35 and 40, you are likely to experience primary ovarian insufficiency, or early menopause.

However, the reason I encourage women not to ignore irregular periods before the age of 45 is because irregular periods at a younger age are more likely to be caused by something else. And that something else should, if possible, be identified and treated. The Seattle Midlife Women’s Health Study found that only 10% of women experienced menstrual changes before age 35. Another 27% experienced changes between the ages of 35 and 39. And it is critical to note that those changes were not menstrual irregularity. The menstrual changes women saw most often before age 40 were heavier, more closely spaced periods.

The takeaway: Irregular menstrual periods before age 45 are likely to be caused by something other than perimenopause and should be evaluated by your doctor. Menstrual cycles longer than 60 days that are due to perimenopause indicate that your last menstrual period will likely be in the next one to three years.