Simultaneous transfer of one good-quality and one poor-quality cleavage stage embryo does not improve pregnancy outcomes.

Embryo quality and quantity are key factors that determine the success of IVF-ET. Yet it is still unclear if, for those patients with only one good-quality embryo in an IVF cycle, the inclusion of a poor-quality embryo increases the procedure's success rate. This is a common question for both clinicians and patients in determining their course of treatment. The purpose of this work was to answer this intriguing question in the context of prognosis of patients undergoing fresh cycles with only one good-quality and more than one poor-quality cleavage-stage embryos. To control for confounding effects, we only included patients at similar age, body mass index (BMI), level of basal follicle stimulating hormone (FSH) and endometrial thickness from January 2015 to June 2021. A propensity score-matched analysis was performed to extract the matched pairs. Then we evaluated pregnancy outcome, including the rate of clinical pregnancy, live birth, embryo implantation, early miscarriage, and ectopic pregnancy. We found that the clinical pregnancy rate (34.8 vs. 38.0%, p = 0.553), live birth rate (27.1 vs. 29.9%, p = 0.598), early miscarriage rate (18.1 vs. 9.5%, p = 0.171) and ectopic pregnancy rate (1.3 vs. 1.2%, p = 1.000) did not significantly differ between those two groups, notwithstanding significant difference of the implantation rate (34.8 vs. 21.3%, p <0.001). Our work indicates that, for prognosis patients at approximately 34 years old with only one good-quality embryo, having additional poor-quality embryos does not seem to help to improve ART success rates per intended embryo transfer. In conclusion, we found that simultaneous transfer of one good-quality and one poor-quality cleavage stage embryo does not improve pregnancy outcomes.