Is it normal to miss a period? How many periods you can miss before you should worry

• If you've missed more than three periods in a row, you should consult a doctor or gynecologist.
• If your missed period is due to birth control you could be at an increased risk of bone loss.
• Common reasons you might miss your period include pregnancy, excessive exercise, and menopause.

Missing one or two periods is completely normal, and not generally a cause for concern. But if you've missed more than a few months, it's time to see your doctor.

Why you don't want to go too long without your period

Missing your period for more than a few months could be a sign of something more serious.

"Absent periods due to long-term use of the Depo-Provera injection and Nexplanon implant, both forms of birth control, can lead to bone loss," says Regina Cardaci, PhD, RN, at NYU Rory Meyers College of Nursing.

Although missing your menstrual cycle does not cause ovarian cancer, Janette Nesheiwat, MD, a family and emergency doctor, says there may be a link with a history of irregular cycles.

Because of the increased risk of serious health complications, she recommends seeing your doctor if you miss more than two periods. "Early evaluation and diagnosis can possibly lead to better outcomes," says Nesheiwat.

Why you might miss a period

Amenorrhea is the term doctors refer to when a woman has missed three or more menstrual periods in a row.

It makes sense to chalk up a missed period to pregnancy if you're sexually active. But the list of what causes amenorrhea is a lot longer than you might think, says Sherry Ross, an obstetrician-gynecologist at Providence Saint John's Health Center.

• Pregnancy and breastfeeding: Pregnancy is the most common cause of a missed period. Also, if you're breastfeeding, it's not uncommon to miss your period. You should resume regular periods when you stop breastfeeding.
• Hormonal birth control: Ross says one of the side effects of low-dose birth control pills is a light or non-existent period. Progesterone-only forms of contraception like the Mirena IUD, Nexplanon implant, and Deprovera may also cause light or non-existent periods.
• Excessive exercise, weight change, stress: These can offset hormones and cause you to miss one or more cycles. "One of these hormones is called leptin and is produced in fatty tissue. Excessive exercising and drastic weight changes can decrease the body fat causing this and other hormones to drop contributing to irregular periods," says Ross. Lightening up your exercise routine and gaining the appropriate amount of weight can help restore your menstrual cycle.
• Hormonal problems: Polycystic ovary syndrome and premature ovarian failure are both conditions that are a result of an imbalance in your sex hormones, which prevents you from releasing an egg on a regular schedule, and therefore, disrupts your menstruation cycle. Another condition called Cushing's disease happens when there's too much of the stress hormone, cortisol, in your blood which has also been known to reduce the number of periods in women with the condition.
• Certain medications: At high doses, ibuprofen and naproxen, both anti-inflammatories, reduce the production of a chemical called prostaglandins that trigger the uterus to contract and shed the uterine lining each month. This may result in lighter periods.
• Menopause: Perimenopause and menopause will disrupt your menstrual cycle. If you're between the age of 45 and 55 and you've gone 12 months without a period, the cause is likely menopause. Perimenopause, or pre-menopause, occurs around 40.

Insider's takeaway

If you've missed more than three periods in a row and aren't sure of the cause, reach out to your doctor or OB-GYN. It could be a sign of an underlying health condition like PCOS. It may also put you at an increased risk of bone loss and osteoporosis.