Live birth sex ratios are not influenced by blastocyst-stage embryo transfer.

OBJECTIVE: To analyze the sex ratio of infants born after blastocyst-stage transfer of embryos with normal preimplantation FISH genetic screening.

DESIGN: Retrospective cohort analysis.

SETTING: Large academic assisted reproductive technology center.

PATIENT(S): Two hundred twenty-eight patients undergoing fresh IVF cycle with blastocyst transfer.

INTERVENTION(S): Preimplantation genetic screening for sex complement.

MAIN OUTCOME MEASURE(S): Sex ratio in liveborn infants following blastocyst transfer.

RESULT(S): One thousand thirteen embryos were normal by preimplantation genetic screening of chromosomes 13, 15, 16, 17, 18, 21, 22, X, and Y. Four hundred ninety-eight normal embryos were transferred to 228 patients with an overall live birth rate of 41.7%. Transferred blastocysts were selected based upon morphologic assessment. When controlling for the sex of the blastocyst embryo, there was no difference in the male-to-female delivery rate per embryo transferred (27.3% vs. 21.4%) (relative risk =1.28, confidence interval 0.93-1.74). Of the live births 51.7% were male and 48.3% were female (P=.61). Subanalysis revealed no difference in male-to-female delivery rates in groups with a 1:1 ratio of male:female embryos transferred, a non 1:1 ratio transferred, or single-sex transfers.

CONCLUSION(S): Blastocyst-stage embryo transfer does not influence the live birth sex ratio of embryos with normal preimplantation FISH genetic screening.