Comparison of clinical outcomes and predictive model analysis between short-term culture and overnight culture after embryo recovery at cleavage stage

This study investigated pregnancy outcomes in patients undergoing Frozen-Thawed Embryo Transfer (FET) with short-term culture (SC) versus overnight culture (OC) and developed a nomogram prediction model for clinical pregnancy. A retrospective analysis of 1962 FET cycles from January 2016 to October 2023 was conducted. Propensity score matching (PSM) was used to balance baseline characteristics between SC and OC groups. Results showed that the SC group had higher biochemical pregnancy, clinical pregnancy, and implantation rates compared to the OC group, but no difference in live birth rates due to a higher early abortion rate in the SC group. Logistic regression identified infertility years, female age, progesterone (P) levels, number of high-quality embryos, and culture time as independent factors influencing clinical pregnancy. A nomogram model was constructed and demonstrated moderate predictive ability (AUC = 0.623). Calibration curves indicated good agreement between predicted and observed probabilities. Decision curve analysis (DCA) and clinical impact curves (CIC) confirmed the model's clinical utility, particularly at threshold probabilities of 0.16-0.42. These findings provide valuable references for optimizing FET strategies and predicting clinical pregnancy outcomes.