To evaluate the impact of day 4 double embryo transfer (DET) with a fully compacted morula (FCM) and a partially compacted morula (PCM) versus day 4 single embryo transfer (SET) with an FCM on clinical and neonatal outcomes in fresh cycles.
Key Findings:
No significant differences in clinical pregnancy rate (CPR), miscarriage rate, live birth rate (LBR), cumulative live birth rate (CLBR), monozygotic twin rate, stillbirth rate, and cesarean section rate (CSR) (all P > 0.05).
DET with FCM and PCM was associated with a significantly higher multiple pregnancy rate (MPR) (P < 0.001) and preterm delivery rate (PDR) (OR 4.02, 95% CI 1.75–9.22; P = 0.001).
Among patients aged <35 years or undergoing IVF, outcomes were consistent with overall data, showing no significant differences in CPR, LBR, and CLBR, but a significantly higher MPR in the DET group (all P < 0.001).
Interpretation:
In fresh cycles, no significant differences in CPR, LBR, and CLBR were found between DET with FCM and PCM compared to SET with FCM, but the MPR was significantly higher in the DET group.
Limitations:
Retrospective design may introduce bias.
Potential confounding factors may not be fully controlled despite PSM.
Conclusion:
SET with FCM may be a preferable strategy for balancing clinical and multiple pregnancy rates.
