The goal of this clinical trial is to learn if drug letrozole 5mg for 10 days works better than letrozole 10mg for 5 days for ovarian stimulation in infertile women with PCOS. It will also learn about the safety of drug letrozole . The main questions it aims to answer are:

What medical problems do participants have when taking drug letrozole? Researchers will compare drug letrozole 5mg for 10 days works better than letrozole 10mg for 5 days for ovarian stimulation in infertile women with PCOS

Participants will:

The experimental arm (p1) will be treated with letrozole 5 mg for 10 days. The comparator arm (p2) will receive letrozole 10mg for 5 days for ovulation induction for consecutive 3 months Treatment will start from the 2nd day of menstruation cycle or withdrawal bleeding after the baseline visit and investigations.

Ovarian response will be assessed by trans-vaginal monitoring of follicle growth aroundday 8 and day 11of menstrual cycle

A total number of 80eligible PCOS women will be randomized to either letrozole 5mg for 10 days or letrozole 10mg for 5 days for ovulation induction. The experimental arm (p1) will be treated with letrozole 5 mg for 10 days. The comparator arm (p2) will receive letrozole 10mg for 5 days (Tab letrol 2.5mg -Renata Pharmaceutical. Treatment will start from the 2nd day of menstruation cycle or withdrawal bleeding after the baseline visit and investigations.

Ovarian response will be assessed by trans-vaginal monitoring of follicle growth aroundday 8 and day 11of menstrual cycle.The presence of preovulatory follicle, multifollicular development, the number of developingfollicles, size of largest follicle and endometrial thickness with pattern will be assessed. The woman will then be advised to test for LH surge by urinary LH kit daily until positive and when positive will have intercourse for two days. She will have serum progesterone estimation after 7 days. She will repeat same dose of ovulation induction if she has menstruationand if there are no symptoms of side effect regarding letrozole intake or will do pregnancy test if she misses period. If missed period occurs further visit will be required for serum β-hCG estimation for confirmation of pregnancy. If pregnancy test is positive she will do an USG for fetal cardiac motion around 7-8 weeks.If B-hCG negative I will give the woman Tab. Norethisterone (5mg) (Tab. Normens 5mg - Renata pharmaceuticals) for (7-10) days for withdrawal bleeding. After withdrawal bleeding I will give her previous dose letrozole. In that situation she will define as a case of anovulation. If cyst appears I will do a Transvaginal sonography of that woman in D2 of the cycle to observe the cyst. If cyst persist, I will hold stimulation in that cycle. If cyst disappear I will give stimulation. All subject will receive drugs (Tab. Letrol 2.5mg, Tab. Normens 5mg) from me. I will ensure their proper intake by cell phone and during their visit they will show their blank strip of drug for confirmation. The cumulative data will be subjected to analysis. by Statistical Package for Social Sciences version 27 for Windows (SPSS Inc., Chicago, Illinois, USA).

Inclusion Criteria:

• Diagnosed cases of PCOS women according to Rotterdam criteria.
• Age: 18-35 years old.
• Primary or secondary infertility

Exclusion Criteria:

• Women withother causes of anovulation (AsCushing syndrome, late onset congenital adrenal hyperplasia, uncorrected hypothyroidism, uncorrected hyperprolactinemia).
• Women with other infertility factors like tubal and uterine causes of infertility, endometriosis, undiagnosed per vaginal bleeding (From history and examination).
• History of hypersensitivity to letrozole.
• BMI:< 18.5 kg/m2 and ≥30 kg/m2.
• Male factor infertility.
• Medical disease (uncontrolled HTN, uncontrolledDM, uncontrolledLiver disease, kidney disease).