Ovulation is the release of a mature egg from the ovary, usually once per menstrual cycle.
What happens during ovulation
During the first half of the menstrual cycle, several small follicles in the ovary begin to mature. Usually one becomes dominant, and once it is ready, a surge in luteinising hormone (LH) triggers the egg’s release. The egg then travels toward the fallopian tube, and this opens the fertile window, the time when conception is most likely. Hormones such as LH and FSH work together to coordinate this process with careful timing. After the egg is released, the empty follicle turns into a structure that makes progesterone, the hormone that supports the second half of the cycle. You can read more about the hormones involved on the hormones page.
Why it is often disrupted in PCOS
In PCOS, hormonal imbalance can prevent a follicle from maturing fully. When this happens, the egg may not be released, a situation called anovulation. This is the main reason periods become irregular and fertile windows are hard to predict. Insulin resistance and higher androgen levels can also contribute to this disruption, because both can affect the hormonal signals that control the cycle. Everyone is different, so some women with PCOS still ovulate occasionally while others rarely do. For the bigger picture of the condition, see what is PCOS.
How ovulation is confirmed
Period dates alone do not always show whether ovulation actually happened. A doctor can use a progesterone blood test timed within the cycle, or ultrasound monitoring, to assess this more accurately. Home methods, such as temperature charting or LH detector kits, are also used by some people. However, interpretation can be difficult when cycles are irregular, because the expected pattern may not appear clearly. For that reason, home methods work better as a rough guide than as firm proof, and they are most useful when read together with other information.
When to talk to a doctor
If your cycles are irregular or you are planning a pregnancy, a doctor can explain the options that suit your situation. Any plan to restore ovulation, including medicines or lifestyle changes, should be discussed with a doctor or pharmacist so it is safe and appropriate. More about fertility and ovulation is on the PCOS and fertility page.
This glossary is education, not diagnosis. For your own situation, ask a doctor or pharmacist.