Any patients in either arm with an E2 serum level >5,000 pg/ml on the day of expected trigger administration will be excluded from the study. These patients will be individually assessed by their primary physician. Their primary physician will decide the safest trigger option based on the patient's risk of OHSS. From our own clinical experience, we expect that <5% of subjects will have an E2 serum level of >5,000 pg/ml and be excluded.