30 patients undergoing IVF using a GnRH antagonist protocol that present with a high response to gonadotrophin stimulation, will be randomized into one of two groups: group A - withdrawal of gonadotrophin support and continue a daily dose of 0.25 mg of the GnRH antagonist. group B - withdrawal of gonadotrophin support and continue a double daily dose of 0.5 mg of the GnRH antagonist.