How many embryos should be transferred? A validated score to predict ongoing implantation rate.

Abstract Objective To developed a prognostic score to predict ongoing implantation rate according to clinical and biological parameters and to choose the number of embryos to be transferred in patients undergoing IVF/ICSI. Study design The transfer score was established using multivariate analysis of biological and clinical parameters in 3211 fresh embryo transfers in a retrospective study. Then we validated the score in 694 fresh embryo transfers in a prospective study. We assessed ongoing implantation rates, ongoing pregnancy rates, multiple pregnancy rates and live birth rate. Results Among the different variables tested, 4 were identified that influenced the implantation rate: female age, the ratio of retrieved oocytes/mean daily dose of injected FSH, attempt rank and the morphology of the embryo cohort. Prospective application of this score resulted in significantly lower number of transferred embryos (1.8 vs 2.0 P P Conclusion Although the risks of multiple pregnancies should not be ignored, it appears excessive to impose the limit of 2 embryos for transfer particularly in situations with a poor prognosis. We sought to provide a personalized prognosis by using clinical and embryo data in order to choose the number of embryo(s) for transfer with a moderate multiple pregnancy rate of less than 11%.