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.