Why does polycystic ovary syndrome cause irregular periods?

In a typical cycle, communication between the brain, ovaries and uterus helps an egg mature and triggers ovulation. Polycystic ovary syndrome can alter this hormone pattern. Follicles may begin developing without one becoming ready to release an egg, or ovulation may happen unpredictably. When ovulation is delayed or does not occur, the usual rise in progesterone is absent or delayed. The uterine lining can then build for longer before bleeding occurs, which may lead to widely spaced, unpredictable or sometimes heavier periods.

Irregular periods is a very common presentation of polycystic ovary syndrome. The condition can also involve acne, increased facial or body hair, scalp hair thinning or difficulty becoming pregnant, but symptoms vary and not everyone has the same pattern. Having irregular periods alone does not establish the cause; pregnancy, thyroid disorders, stress, changes in weight, certain medicines and other reproductive conditions can also affect cycle timing.

Track the first day of each bleed, how long bleeding lasts, and any spotting, pain or other symptoms. Bring this record to a clinician. They may ask about pregnancy possibility, medicines, recent health changes and signs of androgen-related symptoms, then choose tests based on your history. Treatment is tailored to your goals, such as making bleeding more predictable, protecting the uterine lining, managing unwanted hair or acne, or planning a pregnancy. Do not start hormones or other period treatments without medical advice, especially if pregnancy is possible.

Arrange a medical review if your periods become irregular, stop unexpectedly, or change from your usual pattern, because identifying the cause helps guide safe treatment. Seek urgent care for bleeding that is soaking through protection repeatedly, severe or worsening pelvic pain, fainting, marked weakness, or bleeding during pregnancy. A clinician should also assess prolonged gaps between periods; the uterine lining may need protection when ovulation is infrequent.

You could ask: What other causes of irregular bleeding should be checked? How will we know whether I am ovulating? Do I need a plan to protect the uterine lining? Which treatment fits my pregnancy plans and other health needs? What bleeding or pain changes should prompt urgent help?