How Menstrual Cycles Shed Light on Our General Health

New research by Our Bodies Ourselves content expert Shruthi Mahalingaiah, Ana K. Rosen Vollmar, and Anne Marie Jukic suggests that the menstrual cycle might be a vital sign -- a measurable bodily function, like pulse or respiratory rate, that show how well our bodies are working. In this article from the Mahalingaiah Lab, OBOS content expert Eliana Huffman summarizes those findings.

Changes in the menstrual cycle can signal changes in our health. But to recognize those changes, we first need to know what is normal for us. What’s normal for one person may be different from what’s normal for another person. For instance, a “regular” cycle starts around the same time every month but it can vary by up to nine days. This is why it’s important that we monitor our own cycle, making note of when it starts, how much we bleed, how long it lasts, and the symptoms we experience.

While a change in our menstrual cycle may not be cause for concern, it can signal changes in our bodies and potential health problems. Perimenopause, breastfeeding, stress and lifestyle changes, and exposure to chemicals can affect our cycles. Changes or irregularities in our cycles can also be linked to health conditions such as PCOS, thyroid disease, diabetes, eating disorders, and some cancers.

Tracking our menstrual cycle can help us see these patterns, take ownership of our health, and seek support if we think something might be wrong.

Think of your period like a “monthly report card” for your body. If things are going smoothly, your period usually comes in similar intervals – often monthly, but as short as 21 days apart to as long as even 35 to 38 days apart. If your periods start to change, like arriving late or causing a lot of pain, it might be a signal that something in your body needs attention.

SOURCE: Harvard T.H. Chan School of Public Health • AUTHOR: Eliana Huffman • LAST UPDATED: July 18, 2025