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.

Key Words: Sex ratio, gender ratio, sex selection, blastocyst, PGS, IVF outcomes, pregnancy, live birth