Polyendocrine metabolic ovarian syndrome (PMOS) is a hormone imbalance that can affect ovulation. It used to be called polycystic ovary syndrome (PCOS). The word syndrome means a group of symptoms. People with PMOS may have no periods, irregular periods, or very long or heavy periods.

Your eggs are stored in your ovaries. Each egg is in a capsule called a follicle. Normally during the reproductive years, one follicle grows to make a mature egg each month. This egg is released during ovulation and the follicle dissolves.

With PMOS, the hormones that control ovulation are out of balance. These include estrogen, progesterone, and androgen. As a result, ovulation may not occur. Instead, the follicle stays enlarged. This is a fluid-filled sac called a cyst. Over time, the ovaries may fill with many small cysts. When this happens, the ovaries are called polycystic ovaries. In some people, the ovaries also make too much androgen.

Those who have PMOS may also have one or more of these symptoms:

• Acne
• Hair growth on the face and other parts of the body
• Patches of thick, velvety, dark skin (acanthosis nigricans), often on the neck or groin area
• Trouble getting pregnant (fertility problems)
• Weight gain, often around the waist

Those with PMOS are also at greater risk of having cancer of the uterine lining, diabetes, and heart disease.