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.