A menstrual cycle in which the ovary does not release an egg.
What happens during anovulation
In a typical cycle, one follicle matures and releases an egg (ovulation) around mid-cycle, after which progesterone rises to prepare the body for a possible pregnancy. When anovulation happens, this process does not complete, so no egg is released and progesterone does not rise as it normally would. As a result, the uterine lining may build up without a regular shedding, which can lead to longer cycles or unpredictable bleeding. This is why a cycle without ovulation often looks different from a typical one, even when some bleeding still occurs.
How it relates to PCOS
In PCOS, hormonal imbalance frequently disrupts follicle maturation, which makes anovulation a common reason for periods that are infrequent, irregular, or absent, as well as for difficulty conceiving. Small follicles may form but not mature fully enough to release an egg. A doctor can assess this from your cycle pattern, a progesterone blood test in the second half of the cycle, or ultrasound monitoring. It is read together with your symptoms and history, not as a single number. See the PCOS symptoms page for more context.
Signs you might notice
Anovulation often shows up as periods that are infrequent, very long, or unpredictable, and sometimes as bleeding that arrives without the usual premenstrual signs. Some women still bleed even without ovulating, so the presence of a period alone does not confirm that ovulation happened. Other signs, such as changes in cervical mucus, may also be less clear when ovulation does not occur. Because ovulation is needed to conceive naturally, anovulation is a common reason for difficulty getting pregnant in PCOS. Read more on the PCOS and fertility page.
What is usually discussed with a doctor
If ovulation is infrequent, a doctor will look into why through your menstrual history, hormone tests, and sometimes ultrasound, because factors such as thyroid or prolactin can also be involved. For those trying to conceive, there are options that can help restore ovulation, but those choices depend on each person’s situation and are decided with a doctor rather than started on your own. For those not planning pregnancy, irregular cycles are still worth discussing because they relate to long-term uterine health and hormone balance.
This glossary is education, not diagnosis. For your own situation, ask a doctor or pharmacist.