Intensified ovarian stimulation in a GnRH antagonist protocol with agonist triggering: a prospective, clinical...

The threat of severe ovarian hyperstimulation syndrome (OHSS) and the increase in discomfort for the patient has limited the feasibility of maximizing the oocyte yield per treatment cycle. A gonadotrophin-releasing hormone (GnRH) antagonist protocol with agonist triggering and vitrification of all 2PN oocytes can eliminate the risk of OHSS. This prospective, single-centre, cohort study in 30 good-responder IVF patients ≤ 36 years reports the feasibility of arbitrarily intensifying stimulation in a GnRH antagonist protocol in terms of tolerability, safety and efficacy. Ovarian stimulation was performed with 225-375IU FSH, induction of final oocyte maturation with 0.2mg GnRH agonist followed by vitrification of all 2 pronuclear (2PN) oocytes and repetitive vitrified-warmed embryo transfer cycles. Main outcomes were severe OHSS incidence, tolerability, assessed by a questionnaire, and cumulative live birth rate. On average, 17 oocytes were retrieved (range 4-42) and 8.4 oocytes at the 2PN stage were cryopreserved (range 3-22). No case of severe OHSS was observed (0%, 95 CI 0-11.4%). Tolerability was good. The cumulative live birth rate per patient undergoing at least one vitrified-warmed embryo transfer was 26.9% (7/26, 95% CI 13.7-46.1%). This approach can be explored in future larger-sized controlled studies.