In PCOS, many small, fluid-filled sacs grow inside the ovaries. The word “polycystic” means “many cysts” these sacs are actually follicles, each one containing an immature egg. The eggs never mature enough to trigger ovulation. The lack of ovulation alters levels of estrogen, progesterone, FSH, and LH. Estrogen and progesterone levels are lower than usual, while androgen levels are higher than usual. Extra male hormones disrupt the menstrual cycle, so women with PCOS get fewer periods than usual. PCOS is a “syndrome,” or group of symptoms that affects the ovaries and ovulation.