ABSTRACT Purpose To develop a simulation model to guide single embryo transfer (SET) versus double embryo transfer (DET) decisions by minimizing twin risk per transfer while maintaining treatment efficiency. Methods This retrospective observational study included individuals undergoing SET or DET with frozen blastocysts in hormone replacement therapy. Three generalized estimating equation‐based models were developed: ongoing pregnancy after SET (Model 1) and DET (Model 2), and twin pregnancy after DET (Model 3). Model 1 was constructed using propensity score‐matched SETs comparable to DETs. The simulation aimed to identify the optimal transfer sequence for patients with multiple blastocysts using a stepwise optimization that selects SET or DET at each transfer while maximizing pregnancy probability and constraining twin risk below predefined thresholds. Results 5721 DET and 5719 matched SET cycles were included in the analysis. The ongoing pregnancy rate was 20.1% in matched SET and 25.1% in DET, while the ongoing twin pregnancy rate following DET was 5.5%. Area under the curve was 0.77, 0.73, and 0.82 for Model 1–3, respectively. Simulation demonstrated an optimal sequence combining SET/DET under the individualized twin risk in a variety of scenarios ( https://sites.google.com/view/det‐simulator/ ). Conclusions This model supports individualized embryo transfer planning by balancing treatment efficiency and twin risk.
Onishi et al. (Thu,) studied this question.