Adjuvant Therapy With Letrozole in Induction of Ovulation With Polycystic Ovarian Syndrome

Inclusion Criteria: * PCOS will based on European Society of Human Reproduction and Embryology/American Society for Reproductive Medicine (ESHRE/ASRM) criteria, the diagnosis is made when at least two of the following criteria are met: * oilgo and/or anovulation (infrequent or no ovulation), * clinical and/or biochemical signs of hyperandrogenism including hirsutism, acne and/or increased testosterone levels * polycystic ovaries on ultrasound (defined as those containing at least 12 follicles measuring 2-9 mm in diameter arranged peripherally around an echo-dense stroma and/or with increased ovarian volume of at least 10 ml). Exclusion Criteria: * Other causes of hyperandrogenism mimic PCOS such as congenital adrenal hyperplasia, Cushing's syndrome, or androgen secreting tumors are excluded. * Persistent hyperprolactinemia, * thyroid dysfunction defined as TSH \< 0.2 mIU/ML or \>5.5 mIU/mL) * patients with menopausal levels of FSH (\> 15 mIU/mL) (A normal level within the last year is adequate for enter the study). * Liver disease is defined as AST or ALT \> 2 times normal or total bilirubin \>2.5 mg/dL, #kidney disease defined as BUN \> 30 mg/dL or serum creatinine\> 1.4 mg/dL or significant