Polycystic ovary syndrome (PCOS) is a medical condition that can affect a woman’s menstrual cycle, hormones, ability to have children, heart, blood vessels, and appearance (especially excessive hair growth). Although women do produce small levels of androgens, sometimes called male hormones, women with PCOS typically have high levels of androgens. They usually have missed or irregular periods and their ovaries can be swollen with many small cysts. It is estimated that 6 to 10% of all women of reproductive age have PCOS, and evidence suggests that it may run in some families.
A woman’s ovaries have follicles, which are tiny sacs filled with liquid that hold her eggs. These sacs also are called cysts. For most women, approximately 20 eggs start to mature every month, with only one maturing fully. As this one egg grows, the follicle accumulates fluid in it. When the egg is mature, the follicle breaks open and releases it. The egg then travels through the fallopian tube for fertilization. When the single egg leaves the follicle, ovulation takes place.
In women with PCOS, the ovary doesn’t produce all of the hormones it needs for any of the eggs to fully mature. Follicles may start to grow and build up fluid, but no one follicle becomes large enough. Instead, in some but not all women, some follicles may remain as cysts. Since no follicle becomes large enough and no egg matures or is released, ovulation does not occur and the hormone progesterone is not made. Without progesterone, a woman’s menstrual cycle is irregular or absent. Additionally, the cysts make male hormones, which also prevent ovulation.
Lack of ovulation is usually the reason for fertility problems in women with PCOS. Several medications that stimulate ovulation can help women with PCOS become pregnant. Even so, other reasons for infertility in both the woman and man should be ruled out before fertility medications are used. Diet and weight loss are essential for overweight women.