Approximately 25% to 35% of couples that seek infertility services suffer from defects in ovulation.This diagnosis represents the single leading cause of infertility disorders, and makes medical ovulation induction the most common intervention for the treatment of infertility. There are two classes of correctable ovulation defects, and correct classification is correlated with treatment and prognosis. World Health Organization (WHO) I patients have ovulation defects associated with low estrogen and low gonadotropin levels and fail to exhibit withdrawal bleeding after progestin challenge. WHO II ovulation disorders occur in estrogenized/androgenized women who, in general, menstruate. Other names for these conditions include hypogonadotropic hypogonadism (WHO I) and polycystic ovarian disease (WHO II).