373 women with PCOS undergoing a trial of IVF/ICSI will receive OCP from day 2 of the preceding cycle for 21 days followed by GnRH antagonist COH. Another 373 women with PCOS undergoing a trial of IVF/ICSI will start GnRH antagonist COH directly without OCP pretreatment. Both groups will be followed up for effect on ongoing pregnancy rate.

The study will include 740 women with polycystic ovary syndrome undergoing IVF/ICSI cycle using flexible antagonist protocol. Randomization: Patients fulfilling the inclusion criteria will be randomized to two groups. Study Group: This group will include 373 women with PCOS undergoing a trial of IVF/ICSI. This group will receive OCP from day 2 of the preceding cycle for 21 days followed by GnRH antagonist COH. Control Group: This group will include 373 women with PCOS undergoing a trial of IVF/ICSI. This group will start GnRH antagonist COH directly without OCP pretreatment. Random allocation sequence generation: A computer generated list via MedCalc ® Software, version 13.2.2 will be used, assigning each participant number to either study groups. Allocation Concealment: Assignment will be done by sequentially numbered, otherwise identical, sealed envelopes (SNOSE), each containing a 2-inch by 2-inch paper with a written code designating the assigned group. These papers will be placed in a folded sheet of aluminum foil fitted inside the envelope. Effort will be taken to assure absence of any detectable differences in size or weight between intervention and control envelopes. Envelopes will be chosen to be opaque and lined inside with carbon paper. Envelopes will be opened sequentially only after writing the subject's tracking information on the envelope so that the carbon paper served as an audit trail. IVF/ICSI cycle will be done using flexible anatgonist protocol in both groups. Primary outcome will be ongoing pregnancy rate. Secondary outcomes will be biochemical and clinical pregnancy rates.