The Effect of Assisted Reproductive Technologies on Human Sex Ratios

Modern assisted reproductive technology (ART), including pre-implantation genetic testing for aneuploidy (PGT-A), has opened new avenues in understanding early embryonic events and has simultaneously raised questions about the impact of ART itself on sex ratios.

The primary aim was to investigate whether patient demographic characteristics, ovarian stimulation protocols or laboratory characteristics in ART influence sex ratios. The secondary aim was to relate the blastocyst sex ratio (BSR) to the corresponding secondary sex ratio (SSR) in our patient cohort.

We conducted a retrospective single-centre cohort study on consecutive PGT-A cycles from January 2019 to February 2022. We analysed demographic data, stimulation protocols, laboratory characteristics and pregnancy outcomes.

The euploidy rate was 45.1% (2608/5777), BSR 1.07 and euploid BSR 1.03. There was no statistical difference in the ploidy status of XX and XY blastocysts and on multivariate logistic regression analysis, there was no association between euploidy and BSR or any other variables examined, including female age and stimulation protocol. The SSR was 1.02 (1294 embryo transfers) with no statistical difference in biochemical pregnancy (p = 0.41), clinical pregnancy (p = 0.56), miscarriage (p = 0.65) or live birth rates (p = 0.40) based on embryo sex.

Our study indicates that the euploid BSR is not skewed by sex, and there is no relationship between BSR and euploidy, patient characteristics or stimulation protocols. Pregnancy outcomes did not vary by sex, and the SSR was consistent with the SSR of the general Australian population at birth.