Is a Shorter Cycle a Sign of Perimenopause?

During perimenopause, I thought periods were supposed to get farther apart. In the past year, I’ve gone from a regular 28-day cycle to periods every 20 to 24 days (far too often!). Is this the start of perimenopause? Or is something else going on?
—Almost 47, and ready to be done!

In conversation, the term “perimenopause” gets tossed around a lot and is often used to describe all manner of changes women see in their menstrual cycles in their 40s and 50s. But technically, perimenopause has specific definitions.

In early perimenopause, cycles become irregular, meaning that from the first day of one period to the first day of the next period varies in length from month to month by more than seven days. For example, you might have a 28-day cycle followed by a 37-day cycle followed by a 22-day cycle. Early perimenopause varies in length from one woman to another.

Late perimenopause is defined as having gone more than 60 days without a period. This is a sign that your ovaries are winding down and you can expect to experience menopause in one to three years.

What you are experiencing does not meet either of those criteria. To me this sounds like the late-reproductive stage. A short but regular cycle is the hallmark of this stage in our reproductive lives.

While it can certainly feel like you are getting your period all the time, cycles that are 21 days or longer are considered normal. If you are regularly having cycles that are less than 21 days, you should have an evaluation with your doctor. Cycles that short may not be related to your reproductive stage at all. Both structural and hormonal changes — for example, hypothyroidism — can cause too-frequent periods and often warrant treatment. If your periods are frequent and heavy, you should also be evaluated for iron-deficiency anemia.

Ultimately, short regular cycles are not indicative of perimenopause but are likely a sign of the late-reproductive stage. Menstrual cycles that are shorter than 21 days are considered abnormal and should prompt a consultation with your doctor.