Endometrial sampling is performed using the standard technique in the outpatient department. Similarly, superovulation with gonadotrophins will be performed according to our standard practice.Endometrial sampling will be done in the follicular phase not later than day 10 of the cycle. Endometrial sampling will be performed using Pipelle sampling catheter. The Pipelle is inserted gently through the cervical canal into the uterine cavity and advanced slowly till just resistance felt by the operator. Then, the piston is withdrawn to create negative suction and gentle movement of Pipelle up and down in the uterine cavity is performed while it is against the uterine wall. The Pipelle catheter is withdrawn gently and any obtained specimen will be sent for histopathological examination.