GNRH1 and ovarian hyperstimulation syndrome: By combining the results from available trials evaluating freeze-all strategies or donor patients (13 studies, 1908 patients) in which GnRH agonist was used for triggering final oocyte maturation and no luteal phase support was administered (freeze-all strategy), the estimated incidence of severe OHSS was 0.00 (95% CI 0.00–0.00) (Tarlatzis and Bosdou, 2017), although sporadic cases of OHSS under this approach have also been reported (Kol, 2011).