Regardless of age, women can experience irregular or missed periods. The average cycle can last anywhere between 25 to 40 days, and if you miss your period for three or more months, it’s time to talk to your doctor.

It is important for women to track their periods, either on a phone app or on a calendar, they should also keep tabs on changes to flow, especially if their period gets heavier.

Though a missed period can cause panic, for the most part, they shouldn’t cause major concern. And if you’re not pregnant, there are five other reasons you may skip a cycle.

Your stress levels change

Stress, from the anxiety that comes from studying for exams to dealing with a loss of a family member, can change a woman’s period making it irregular, delaying it or causing it to disappear altogether.

It could be PCOS

Polycystic ovarian syndrome (PCOS) is a hormonal disorder that can affect up to 10 per cent of women. PCOS leads to more estrogen in the body that can interrupt the usual flow of estrogen, which means eggs won’t get released from the ovaries during a cycle.

PCOS can be diagnosed with a blood test, so if you notice other symptoms besides the missed period, talk to your doctor. Nutrition is also important. If you have PCOS, you should focus on eating a healthy diet and increasing your daily exercise.

Hypothalamic amenorrhea is another cause

Also called “female athlete triad,” this condition is very common for female athletes and it can cause missed periods. We see it in ballet dancers and athletes, it’s about energy-level imbalance. Our bodies tend to prioritize what’s important and if highly competitive athletes are using energy for other things, reproduction is not prioritized.

Hypothalamic amenorrhea is also common for people on very restrictive diets or those with eating disorders like anorexia. In this case, a proper diet change is required, as is cutting down on the amount of exercise you do.

Maybe it’s your ovaries

Primary ovarian insufficiency (POI), which was previously called premature ovarian failure, is a condition where women lose the function of their ovaries before the age of 40.

This can be caused by types of chemotherapy from childhood cancer, genetics or other autoimmune disorders. A blood test is the best way to see if you have POI.

Changes with your pill and other contraceptives

Kirkham says women who begin a new routine of a birth control pill or IUD may experience normal changes in their period flow.

“Sometimes you have to go on the pill to regulate the period. If you go off, you go back to the original problem.”

Other reasons women may miss their periods can include taking certain anti-depressant medication, being obese or having a benign tumour called prolactinoma, which is quite rare. Kirkham says the best thing women can do is to alert their health-care provider as soon as they notice changes.