Influence of embryo sex on development to the blastocyst stage and euploidy

Objective: To compare the prevalence of blastocyst development and euploidy in XX versus XY embryos. Design: Retrospective cohort study. Setting: Boston IVF, a large university-affiliated reproductive medicine practice. Patient(s): All patients who underwent their first preimplantation genetic screening cycle between January 1, 2006, and December 31, 2007. Intervention(s): In vitro fertilization and preimplantation genetic screening. Main Outcome Measure(s): Proportion of embryos that developed to the blastocyst stage by day 5 and prevalence of euploidy for chromosomes 8, 13, 14, 15, 16, 17, 18, 20, 21, and 22 in XX versus XY embryos. Result(s): Seven hundred fifty-eight embryos from 138 cycles in 138 patients were analyzed. Three hundred sixty-six (48%) were XX, and 392 (52%) were XY. XX and XY embryos were equally likely to develop to the blastocyst stage by day 5 and were equally likely to be euploid for the analyzed chromosomes. Conclusion(s): Our data suggest that extending embryo culture to day 5 does not lead to sex selection and that euploidy and aneuploidy are not sex dependent. (Fertil Steril (R) 2011; 95: 936-9. (C) 2011 by American Society for Reproductive Medicine.)