Partner Ethnicity and Assisted Reproductive Technology Outcomes: A Retrospective Cohort Study

<b>Background:</b> Despite significant advances in assisted reproductive technology (ART), disparities in clinical outcomes persist. While patient-related factors are well-studied, the role of partner ethnicity remains understudied. We hypothesized that partner ethnicity affects ART outcomes. This study examined the association between partner ethnicity and ART outcomes. <b>Methods:</b> We conducted a retrospective cohort study among patients and their partners undergoing IVF treatment in the United Kingdom between 2017 and 2018. The exposure was partner ethnicity. Outcomes included biochemical pregnancy, clinical pregnancy, pregnancy loss, and live birth. We calculated risk ratios (RR) and 95% confidence intervals (CI) using multivariable regression models to estimate the association between partner ethnicity and IVF outcomes, adjusting for female patient age, partner age, patient ethnicity, gravidity, infertility diagnosis, treatment type, preimplantation genetic testing for aneuploidy, and number of prior in vitro fertilization (IVF) cycles. <b>Results:</b> Among 158,813 IVF cycles, live birth rates per cycle were 26.3% for couples with White partners and 23.1% for those with non-White partners. Non-White partners were associated with a 5% lower clinical pregnancy rate (RR 0.95, 95% CI 0.92-0.97) and a 6% lower live birth rate (RR 0.94, 95% CI 0.92-0.97). Specifically, Black (RR 0.82, 95% CI 0.77-0.87) and Asian (RR 0.67, 95% CI 0.59-0.76) partners had significantly reduced live birth rates, though these associations were attenuated after adjusting for patient ethnicity. Couples in which both the partner and patient were Black or Asian had 24-42% lower live birth rates compared with White couples (Black: RR 0.76, 95% CI 0.70-0.82; Asian: RR 0.58, 95% CI 0.49-0.68). <b>Conclusions:</b> Partner ethnicity is independently associated with IVF outcomes, with non-White partners showing lower rates of these outcomes. These findings suggest the clinical relevance of partner ethnicity in reproductive outcomes. Further research is warranted to elucidate the mechanisms underlying these associations.