Polycystic ovarian syndrome, or PCOS, is a condition in which a woman’s levels of the sex hormones estrogen and progesterone are out of balance. This leads to the growth of ovarian cysts (benign masses on the ovaries). PCOS can cause problems with women’s menstrual cycle, fertility, cardiac function, and appearance. Symptoms often begin soon after a woman first begins having periods. In some cases, PCOS develops later during the reproductive years, for instance, in response to substantial weight gain. This is the most common characteristic. Examples include menstrual intervals longer than 35 days; fewer than eight menstrual cycles a year; failure to menstruate for four months or longer; and prolonged periods that may be scant or heavy.: Elevated levels of male hormones (androgens) may result in physical signs, such as excess facial and body hair (hirsutism), adult acne or severe adolescent acne, and male-pattern baldness (androgenic alopecia).