That depends.

Some women have regular periods every two months. Others have regular periods every 21 days. So, if your periods aren’t on a 28-day schedule, it may not be a problem at all, as long as it’s regular for you. And your cycle’s schedule may change over time. In your 20s, you may menstruate every 30 days, then every 33 days in your 30s. In  your 40s, the intervals could change again. There’s no one-size-fits-all cycle.

If you’re used to getting your period every 28 days and it’s now 45 days without a sign of menstruation, the first thing you should do is to see your gynecologist.  A blood test (not urine testing) for pregnancy would probably be ordered.

But what if you haven’t been sexually active? Ask yourself, what else in your life has changed? Have you been on a starvation diet? Undergone some very stressful event? If so, mention these changes when you discuss your menstrual cycle with your doctor.  The menstrual irregularity may be the first sign of thyroid dysfunction, or other metabolic or endocrine disorders.

The “take home” message here is that you should always be sure to keep an accurate menstrual calendar every month so you can tell your doctor when your period started, when it ended, when you had intercourse, and when you have spotting.

Speaking of spotting between periods, sometimes it’s a sign of a problem but often it’s not. Certain women will spot right in the middle of their cycles, when they ovulate. This sort of spotting can be perfectly normal. There’s even a German name for it: mittelschmerz,  But, if it continues, even in the middle of your cycle or if you’re spotting at odd intervals, like three days after your period ends, it’s time to make a gynecologist’s appointment.

- Yvonne Thornton, MD, MPH