Polycystic Ovary Syndrome (PCOS)
Polycystic (pronounced pah-lee-SIS-tik) ovary syndrome, or PCOS, is a set of symptoms related to a hormonal imbalance that can affect women and girls of reproductive age.
PCOS may cause menstrual cycle changes, skin changes such as increased facial and body hair and acne, cysts in the ovaries, and infertility. Often, women with PCOS have problems with their metabolism also.
About Polycystic Ovary Syndrome (PCOS)
PCOS is a set of symptoms related to a hormonal imbalance that can affect women and girls of reproductive age.
What is PCOS?
PCOS is a set of symptoms related to a hormonal imbalance that can affect women and girls of reproductive age. Women with PCOS usually have at least two of the following three conditions:1
- Absence of ovulation, leading to irregular menstrual periods or no periods at all
- High levels of androgens (a type of hormone) or signs of high androgens, such as having excess body or facial hair
- Cysts (fluid-filled sacs) on one or both ovaries—"polycystic" literally means "having many cysts"
Some women diagnosed with PCOS have the first two conditions listed above as well as other symptoms of PCOS but do not have cysts on their ovaries.
PCOS is the most common cause of anovulatory (pronounced an-OV-yuh-luh-tawr-ee) infertility, meaning that the infertility results from the absence of ovulation, the process that releases a mature egg from the ovary every month. Many women don't find out that they have PCOS until they have trouble getting pregnant.
PCOS can cause other problems as well, such as unwanted hair growth, dark patches of skin, acne, weight gain, and irregular bleeding.
Women with PCOS are also at higher risk for:2
- Obstructive sleep apnea, a disorder that causes pauses in breathing during sleep
- Insulin resistance
- Metabolic syndrome, a group of risk factors for heart disease and type 2 diabetes
- Type 2 diabetes
- Heart disease and high blood pressure (cardiovascular disease)
- Mood disorders
- Endometrial hyperplasia (pronounced en-doh-MEE-tree-uhl hahy-per-PLEY-zhuh), a condition in which the lining of the uterus becomes too thick, and endometrial cancer
What are the symptoms of PCOS?
In addition to the three features used to diagnose polycystic ovary syndrome (PCOS) (absence of ovulation, high levels of androgens, and ovarian cysts), PCOS has many signs and symptoms, some of which may not seem to be related:1,2
- Menstrual irregularities:
- No menstrual periods—called amenorrhea (pronounced ey-men-uh-REE-uh)
- Frequently missed periods—called oligomenorrhea (pronounced ol-i-goh-men-uh-REE-uh)
- Very heavy periods
- Bleeding but no ovulation—called anovulatory periods
- Excess hair growth on the face, chest, belly, or upper thighs—a condition called hirsutism (pronounced HUR-soo-tiz-uhm)
- Severe, late-onset, or persistent acne that does not respond well to usual treatments
- Obesity, weight gain, or trouble losing weight, especially around the waist
- Pelvic pain
- Oily skin
- Patches of thickened, dark, velvety skin—a condition called acanthosis nigricans (pronounced ay-kan-THOE-sis NY-grih-kanz)
Because many women don't consider problems such as oily skin, extra hair growth, or acne to be symptoms of a serious health condition, they may not mention these things to their health care providers. As a result, many women aren't diagnosed with PCOS until they have trouble getting pregnant or if they have abnormal periods or missed periods.
Although PCOS is a leading cause of infertility, many women with PCOS can and do get pregnant. Pregnant women who have PCOS, however, are at higher risk for certain problems, such as miscarriage. Learn more about PCOS-related pregnancy problems.
What causes PCOS?
Researchers and health care providers know that genetic and environmental factors contribute to the development of polycystic ovary syndrome (PCOS), but do not know exactly what causes PCOS.
Because the symptoms of PCOS tend to run in families, the syndrome is probably caused, at least in part, by a change, or mutation, in one or more genes. Recent research conducted in animal models suggests that in some cases PCOS may be caused by genetic or chemical changes that occur in the womb.1
PCOS likely results from a combination of causes, including genes and environmental factors.
What causes the symptoms of PCOS?
Most of the symptoms of PCOS are caused by higher-than-normal levels of certain hormones, called androgens.
The ovaries produce hormones, which are chemicals that control functions in the body. One of the hormones that the ovaries make is estrogen—sometimes called the "female hormone" because women's bodies make more of it than men's bodies do. The ovaries also make androgens—sometimes called "male hormones" because men's bodies make more of them than women's bodies do. Men and women need certain levels of both hormones for normal health.
In women with PCOS, the hormones are out of balance: these women have higher-than-normal levels of androgens and may have lower-than-normal levels of estrogen. High levels of androgens can:
- Interfere with signals from the brain that normally result in ovulation, so that ovulation does not occur regularly
- Cause the follicles—small, fluid-filled cysts within the ovaries in which eggs grow and mature—to enlarge, forming cysts2
- Produce other symptoms of PCOS, including excess hair growth and acne3,4
Other symptoms of PCOS result from problems with insulin, another of the body's hormones. Insulin helps move sugar (also called glucose) from the bloodstream into cells to use as energy. When cells don't respond normally to insulin, the level of sugar in the blood rises. In addition, the level of insulin goes up as the body produces more and more of it to try to get glucose into the cells. Too much insulin increases the production of androgens,5 which then cause symptoms of PCOS. High levels of insulin can also increase appetite and lead to weight gain.3 High insulin levels are also linked to a skin condition called acanthosis nigricans, which results in thickened dark, velvety patches of skin.3
Women are at higher risk for PCOS if they:
- Have a mother or sister with PCOS
- Are obese
How do health care providers diagnose PCOS?
Health care providers look for three characteristic features of polycystic ovary syndrome (PCOS): absence of ovulation, high levels of androgens, and cysts on the ovaries. Having one or more of these features could lead to a diagnosis of PCOS. If your medical history suggests that you might have PCOS, your health care provider will rule out other conditions that may cause similar symptoms.
Some of these conditions include:
- Excess hormone production by the adrenal glands, called adrenal hyperplasia (pronounced uh-DREEN-l hahy-per-PLEY-zhuh)
- Problems with the function of the thyroid gland
- Excess production of the hormone prolactin by the pituitary gland, called hyperprolactinemia (pronounced hi-per-pro-lak-tuh-NEE-mee-uh).
- Take a full family history. Your health care provider will ask you about your menstrual cycle and any history of infertility. He or she also will ask you whether you have a mother or sister with PCOS or with symptoms like yours, as PCOS tends to run in families.
- Conduct a complete physical exam. Your health care provider will do a physical exam and look for extra hair growth, acne, and other signs of high levels of the hormone androgen. He or she also will take your blood pressure, measure your waist, and calculate your body mass index, a measure of your body fat based on your height and weight.
- Take blood samples. Your health care provider will check the levels of androgens, cholesterol, and sugar in your blood.
- Do a pelvic exam or ultrasound to check your ovaries. During the pelvic exam, your health care provider will insert two fingers into your vagina and press on your belly to feel for cysts on your ovaries. To help see cysts in your ovaries, he or she might recommend an ultrasound, a test that uses sound waves to take a picture of your pelvic area. Your health care provider also will check how thick the lining of your uterus is; if your periods are irregular, the lining of your uterus could be thicker than normal.
Because there is currently no universal definition of PCOS, different expert groups use different criteria to diagnose the condition. However, all the groups look for the following three features:3
- Menstrual irregularities, such as light periods or skipped periods, that result from long-term absence of ovulation (the process that releases a mature egg from the ovary)
- High levels of androgens that do not result from other causes or conditions, or signs of high androgens, such as excess body or facial hair
- Multiple cysts of a specific size on one or both of the ovaries as detected by ultrasound
Your health care provider will use one of three different methods to diagnose PCOS. One method requires only features 1 and 2 above for a PCOS diagnosis; another requires any two of the three features above for a PCOS diagnosis; and the last one requires feature 1, plus one other feature listed above for a PCOS diagnosis.
Is there a cure for PCOS?
There is currently no cure for polycystic ovary syndrome (PCOS), and it does not go away on its own.
Even after menopause, women with PCOS often continue to have high levels of androgens as well as insulin resistance. This means that the health risks associated with PCOS are lifelong.1
What are the treatments for PCOS?
Because polycystic ovary syndrome (PCOS) has a broad range of symptoms, health care providers may use a variety of treatments for this condition and its symptoms.
Because PCOS has a broad range of symptoms, health care providers may use a variety of treatments for this condition and its symptoms.1
The treatment(s) your health care provider suggests will depend on:
- Your symptoms
- Your other health problems
- Whether you want to get pregnant
Because some of the common treatments for PCOS symptoms can prevent pregnancy or may harm the fetus during pregnancy, it's important to discuss your fertility goals with your health care provider while discussing treatment options. Be sure you fully understand your treatment options and their effects on pregnancy before deciding on a course of treatment.
You should also discuss the risks of treatments with your health care provider. All treatments have risks, and some of them can be serious. Also, some unhealthy lifestyle factors such as smoking can increase these risks, and thus you should discuss with your health care provider the best way to eliminate these practices.
Treatments for Infertility Resulting from PCOS
In most cases, fertility problems in women with polycystic ovary syndrome (PCOS) result from the absence of ovulation (anovulation), but anovulation may not be the only reason for these problems. Before beginning treatment for infertility possibly related to PCOS, be sure that your health care provider rules out other causes.1
Lifestyle changes, such as losing weight, can trigger body changes that facilitate conception in women with PCOS.2,3 Your health care provider may recommend that you try weight loss and other lifestyle changes before trying any medications to see if fertility returns and pregnancy occurs naturally. Research shows that lifestyle changes can help restore ovulation and improve pregnancy rates among women with PCOS.3,4 Research shows that, among obese women with PCOS who experienced menstrual dysfunction, even losing small amounts of weight improved menstrual function and fertility.5
If you have PCOS-related infertility, your health care provider may prescribe one of the following medications to help you get pregnant.
Treatments to Relieve Symptoms of PCOS
NICHD PCOS Research Goals
NICHD conducts and supports a wide range of research activities to learn more about the causes of polycystic ovary syndrome (PCOS), its risk factors, and its possible treatments.
- Genetics of PCOS. A number of gene variants have been linked to PCOS and its associated conditions. Ongoing NICHD research projects aim to identify genetic variations that underlie the development of PCOS as well as individual responses to PCOS treatments. These projects include genome-wide association studies as well as studies focused on specific gene variations.
- Pathophysiological mechanisms of PCOS. PCOS is characterized by hyperandrogenism (high levels of androgens) and, in the majority of cases, insulin resistance. NICHD is working to understand the cellular and molecular mechanisms of ovarian dysfunction in the context of these hormonal abnormalities. Specifically, NICHD aims to characterize the roles of insulin, androgens, and other hormones in reproductive and metabolic dysfunction. The NICHD studies are using both animal models and human participants.
- Precursors or predictors of PCOS in adolescents. PCOS may be detectable in girls as early as, or even before, their first menstrual periods. Studies are examining early signs of PCOS in adolescents to better understand the relationships among obesity, high androgen levels, and PCOS. This knowledge could help scientists develop early interventions to manage or slow the development of PCOS.
- New treatment strategies for PCOS. NICHD is evaluating the efficacy of both existing and new treatments for PCOS. These studies include pharmacological (drug) and non-pharmacological treatments. In vitro studies are examining the cellular and molecular mechanisms of pharmacological treatments.
PCOS Research Activities and Advances
Are there disorders or conditions associated with PCOS?
Can PCOS lead to cancer?
PCOS increases the risk of some types of cancer.
For instance, some research has shown that risk of cancer of the endometrium (pronounced en-doh-MEE-tree-uhm), the inside lining of the uterus, may be higher for women with polycystic ovary syndrome (PCOS) than it is for women without PCOS.1 Irregular periods, or a lack of periods, can cause the endometrium to build up and become thick. This thickening can lead to endometrial cancer.2,3,4
Data on links between breast cancer, ovarian cancer, and PCOS are limited. While some small studies have suggested that a lack of ovulation, as occurs with PCOS, is linked with an increased risk of breast cancer, other studies have not shown an association.1 While some research has shown more than a doubling of the risk of ovarian cancer in women with PCOS,5 scientists have not confirmed these links in large population studies, and further studies hint that women with PCOS may have a lower risk of ovarian cancer.1,2,6 Therefore, any associations between breast or ovarian cancers and PCOS remain inconclusive.
Learn more about these different types of cancers on the National Cancer Institute website:
If I have PCOS, will I be able to get pregnant?
Even though polycystic ovary syndrome (PCOS) is a leading cause of infertility in women, PCOS-related infertility is treatable in most cases. Women with PCOS can and do still get pregnant—sometimes naturally, sometimes with help.
Visit the Treatments for Infertility Resulting from PCOS section for more information about treatments that help women with PCOS get pregnant.
Does PCOS affect pregnancy?
Women with polycystic ovary syndrome (PCOS) are at higher risk for certain problems or complications during pregnancy. In addition, infants born to mothers with PCOS are at higher risk of spending time in the neonatal intensive care unit or dying before, during, or right after birth. Complications of pregnancy commonly associated with PCOS could be a reason for these risks. Also, conditions common to PCOS like metabolic syndrome and increased androgens may increase the risks affecting infants.1,2
Pregnancy complications related to PCOS include:
- Miscarriage or early loss of pregnancy. Women with PCOS are three times as likely to miscarry in the early months of pregnancy as are women without PCOS.2,3 Some research shows that metformin may reduce the risk of miscarriage in pregnant women with PCOS. However, other studies have not confirmed that metformin reduces miscarriage risk, so more research needs to be done.2,4,5
- Gestational (pronounced je-STEY-shuhn-uhl) diabetes. This is a type of diabetes that only pregnant women get. It is treatable and, if controlled, does not cause significant problems for the mother or fetus. In most cases, the condition goes away after the baby is born. Babies whose mothers have gestational diabetes can be very large (resulting in the need for cesarean, or C-section [surgical], delivery), have low blood sugar, and have trouble breathing. Women with gestational diabetes, as well as their children, are at higher risk for type 2 diabetes later in life.
- Preeclampsia (pronounced pree-i-KLAMP-see-uh). Preeclampsia, a sudden increase in blood pressure after the 20th week of pregnancy, can affect the mother's kidneys, liver, and brain. If left untreated, preeclampsia can turn into eclampsia. Eclampsia can cause organ damage, seizures, and even death. Currently, the primary treatment for the condition is to deliver the baby, even preterm if necessary. Pregnant women with preeclampsia may require a C-section delivery, which can carry additional risks for both mother and baby.5
- Pregnancy-induced high blood pressure. This condition is due to an increase in blood pressure that may occur in the second half of pregnancy. If not treated, it can lead to preeclampsia. This type of high blood pressure can also affect delivery of the baby.
- Preterm birth. Infants are considered "preterm" if they are delivered before 37 weeks of pregnancy. Preterm infants are at risk for many health problems, both right after birth and later in life, and some of these problems can be serious.
- Cesarean or C-section delivery. Pregnant women with PCOS are more likely to have C-sections because of the pregnancy complications associated with PCOS, such as pregnancy-induced high blood pressure.4,6 Because C-section delivery is a surgical procedure, recovery can take longer than recovery from vaginal birth and can carry risks for both the mother and infant.
If you have PCOS and get pregnant, work with your health care provider to promote a healthy pregnancy and delivery.