Cumulative number and morphological score of embryos resulting in success: Realistic expectations from in vitro fertilization-embryo transfer

Objective: To define statistical thresholds for the number and morphological score of embryos transferred that would be predictive of reproductive success in an IVF program. Design: A retrospective review of patient records. Setting: The Mount Sinai Medical Center Assisted Reproductive Technologies Program. Participants: One hundred women who underwent IVF-ET for a diagnosis of tubal occlusion and later delivered viable infants. Results: The mean number of embryos transferred before achieving live birth was 10.7 ± 7.9 (mean ± SD), with one half of patients achieving success within the first seven embryos transferred, and 95% achieving success within 25 embryos. For high quality embryos, the numbers were 7.5 ± 6.3, 5, and 17, respectively, and, for the cumulative embryo score, a measure of both embryo morphology and metabolic activity, were 114.2 ± 86.0, 83, and 280, respectively. Greater than 50% of live births occurred within the first two ET attempts. Conclusions: Although more than half of patients achieved reproductive success within the first two ETs and the first five high quality embryos transferred, after this threshold, fecundity declined rapidly. The calculation of cumulative embryo scores offered additional prognostic information. While all prior attempts to define IVF-ET failure have done so by including patients who did not become pregnant, we have found an analysis of our successes to be a useful adjunct in counseling patients.