Factors Affecting Frozen Embryo Transfer Success Rates

Background This study aims to identify factors influencing the outcomes of frozen embryo transfer (FET) cycles. Methods A prospective observational study was conducted on participants who underwent FET of autologous embryos after endometrial preparation with hormone therapy. Patient characteristics, ovarian stimulation details, and embryo specifics were recorded. Endometrial thickness, morphology, and Doppler flow were assessed on the day of progesterone start. Embryo details on the transfer day were also recorded. Serum ß-hCG levels were measured twelve days post-transfer, and those with levels > 25 IU/L underwent a 6-week ultrasound to detect a gestational sac. The clinical pregnancy rate (CPR) was calculated, and statistical differences between pregnant and non-pregnant groups were evaluated using Chi-square or Fisher’s exact tests for categorical variables and the Mann-Whitney U-test for continuous variables. Logistic regression analysis was used to identify independent variables associated with successful pregnancy outcomes. Results For a total of 190 cycles, the CPR was 35.7%. Univariate logistic regression revealed that antral follicle count (AFC), Anti-Müllerian hormone (AMH), blastocyst transfer, embryo quality, and transferring more than one embryo were significantly associated with CPR. On multivariate analysis, embryo quality remained the only independent predictor of successful FET outcomes. Conclusion Embryo quality is the most significant predictor of successful FET outcomes. Other factors like age, ovarian reserve, number and type of embryo transferred also influence success, further research is needed to understand the role of endometrial factors. Tailored treatment approaches are crucial for optimising IVF success.