Preliminary clinical outcome of novel strategy for the maximization of cumulative pregnancy rates per retrieval in normal responders

OBJECTIVE We devised a novel strategy, a GnRH antagonist protocol with a GnRH agonist trigger followed by frozen-thawed blastocyst transfers with long zona dissection (LZD). The purpose of this study was to investigate the clinical outcomes of this new strategy according to age. METHODS Ninety women aged less than 35 (group A) and 32 women aged 35 to 39 (group B) underwent the GnRH antagonist protocol with a GnRH agonist trigger in order to obtain many oocytes and prevent early-onset ovarian hyperstimulation syndrome (OHSS). All oocytes were cultured to the blastocyst stage and all blastocysts grade 3BB or better were cryopreserved. Embryo transfers were only performed in freeze-thaw cycles to prevent late-onset OHSS and to overcome embryo-endometrium dyssynchrony. LZD was performed just after thawing to improve hatching and implantation rates. RESULTS The average numbers of retrieved oocytes and blastocysts grade 3BB or better were 12.8±5.5 and 4.4±2.6 in group A and 10.9±7.4 and 2.5±2.2 in group B, respectively, and OHSS did not occur in any of the women. Implantation rates were 46.7% in group A and 39.3% in group B. Cumulative clinical pregnancy rates per retrieval were 77.8% in group A and 62.5% in group B. Cumulative ongoing pregnancy rates per retrieval were 71.1% in group A and 53.1% in group B. CONCLUSION GnRH antagonist protocol with GnRH agonist trigger followed by frozen-thawed blastocyst transfers with LZD can generate many blastocysts without OHSS and maximize cumulative pregnancy rates per retrieval. This strategy is more effective in young women aged less than 35 than in women aged 35 to 39.