A woman missing her period is often a sign that she’s pregnant. But for women who aren’t pregnant and keep skipping periods or have irregular cycles, the reason might be polycystic ovary syndrome (PCOS).
PCOS, which affects 1 in 10 women, is a reproductive hormonal imbalance that affects ovulation.
Normally, a woman releases an egg every month as part of her menstrual cycle. With PCOS, eggs may not develop properly, or the ovaries may fail to release eggs regularly.
All reproductive-aged women have tiny cysts on their ovaries, called follicles. Women with PCOS tend to have more of them, hence the word “polycystic.” Women with PCOS can also experience higher levels of androgen, a reproductive hormone that regulates the development of male characteristics, increasing a woman’s risk for excess hair growth and acne.
“PCOS is a syndrome, which means it’s a constellation of symptoms,” says Jennifer Mersereau, MD, a reproductive endocrinologist and infertility specialist at UNC Health Care. “Some people have all the symptoms, and some people have barely any. It’s not one-size-fits-all.”
Diagnosing PCOS
The cause of PCOS is unknown, and diagnosing it can be difficult because some of the symptoms, such as acne and weight gain, are quite common. But Dr. Mersereau says infrequent menstrual cycles—sometimes even just one or two a year—are the key signifier and what typically brings women to the gynecologist.
“While they’re at the doctor, they will be checked for other issues that might mask as PCOS,” she says. “For example, if there’s some type of thyroid dysfunction, that can look a lot like some of the same symptoms. A blood test will rule that out.”
If a PCOS diagnosis is confirmed, a woman will start treatment to help manage symptoms. Birth control pills, a progestin-based IUD or progestin pills taken on an intermittent basis, which will help make the lining of the uterus shed, are all common options.
“It’s really important that women know that they can develop early cancer of the uterus if they aren’t getting access to treatment,” Dr. Mersereau says. This can happen when, as a woman misses more and more periods, the uterine lining gets thicker. This thickening, called endometrial hyperplasia, can cause abnormal precancerous cell growth in the uterus that can eventually turn into cancer.
Another route to relief? Losing weight can sometimes help mitigate symptoms. PCOS has been linked with metabolic issues, though Dr. Mersereau says the relationship between the two aren’t causal. That is, PCOS doesn’t cause the metabolic issues and the metabolic issues don’t cause PCOS.
“We don’t know the cause of PCOS, though some people who have it might also have insulin resistance, are overweight or obese and have an increased risk of diabetes,” she says. “Some people might also notice that their symptoms of PCOS worsen if they gain weight. For example, a woman who has gained 20 pounds might notice her periods become more irregular. And the same is true in reverse: If someone is losing weight, they might notice their periods coming back.”
PCOS and Pregnancy
Because PCOS can disrupt ovulation or cause the egg to develop improperly, it can cause infertility. But having PCOS does not mean that pregnancy is impossible.
“If a woman is skipping her period each month, she should see her gynecologist right away because that means she’s likely not ovulating,” Dr. Mersereau says, which means she won’t be able to get pregnant. In this case, medications can be prescribed to help her ovulate to increase the chance of becoming pregnant.
“Meanwhile, if her periods are coming, for example, every 32 or 35 days, that’s regular enough that she is likely ovulating and potentially could get pregnant,” she says. “I recommend that all women, whether they have PCOS or not, see their health care provider once they are ready to start trying to get pregnant, and whether they need medication to help with ovulation can be addressed then.”
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