The basis for obesity's impact on reproduction is not well characterised and there is a controversy whether the key organ influenced by it are the ovaries or the uterus.

Insulin sensitizers ameliorate insulin resistance in obese patients. This study seeks to determine if Metformin helps to increase fecundability by affecting the uterus in women undergoing ART. As a surrogate marker- flows in the uterus will be tested during the treatment.

Obesity has been long implicated in reduced reproductive potential and it has been shown to impair conception and implantation. However, the basis for this adverse effect is still obscure and there is a controversy whether the key organ influenced by it are the ovaries or the uterus.

It is well established that insulin resistance is one of the main mechanisms of obesity's negative influences on the reproductive organs in females. Insulin sensitizers ameliorate insulin resistance in obese patients.

This study seeks to determine if Metformin ,an oral antidiabetic and insulin sensitizer, helps to increase fecundability by affecting the uterus in women undergoing frozen-thawed embryo transfer compared to the control group. As a surrogate marker- flows in the uterus will be tested during the treatment.

Inclusion Criteria:

• Age: from 18-40 years old.
• BMI > 30
• Infertile women undergoing frozen-thawed embryo transfer in an ART setting
• Women with at least one Top graded embryo
• Normal uterine Doppler indices at time of recruitment.

Exclusion Criteria:

• Diabetes mellitus - uncontrolled.
• Hyperprolactinemia- uncontrolled.
• Hypothyroidism- uncontrolled.
• women who are already treated with Metformin
• women with endometrial factor as the cause for infertility