Mayo Clinic defines menopause as the 12 months following a woman’s last menstrual period. This transition period, which typically happens in a woman’s 40s or 50s, marks the end of her childbearing years. In the United States, the average woman enters menopause at age 51. The months leading up to menopause, called perimenopause, are filled with telltale symptoms, which can range from the sometimes-comical hot flashes to the unpleasant, such as increased belly fat and fatigue.

Some women report mild and short-lived menopause symptoms, or symptoms that came on with some measure of severity subsided over time. For others, these symptoms can be so severe that they interfere with daily routines or activities and may leave women feeling exhausted, frustrated or irritable.

This natural transition can include a wide range of symptoms and signs, but here are five key signals that may mean you’re entering menopaus.

Menstrual Changes

For some women, there is a regular monthly menstrual cycle until the final period. Most, however, will experience noticeable changes in their cycles in the months leading up to menopause. Some women will experience heavier or lighter periods than usual, as well as irregular periods, sometimes missing months of menstrual cycles at a time. Skipping periods during perimenopause is to be expected, but pregnancy still can occur during this time, so if you experience any other symptoms of pregnancy, you should still take a pregnancy test.

If you have not had your period for 12 consecutive months and begin spotting, make an appointment with your gynecologist to check for conditions that the spotting may indicate, including cancer.