Personalized Fertility Strategies: Assessing the Efficacy of HRT vs. Natural Cycle Protocols in Frozen Embryo Replacement

Objective This study compares the effectiveness of hormone replacement therapy (HRT) and natural cycle (NC) protocols in frozen embryo replacement (FER) cycles, focusing on clinical pregnancy rates (CPR) and live birth rates (LBR) while accounting for age and BMI variations. Design A single-centre, retrospective study analysing outcomes over a 12-month period in patients undergoing FER treatment. Setting Fakih IVF Centre, Abu Dhabi, United Arab Emirates. Patients Data from 379 FET cycles were analysed, with 324 patients in the HRT group and 55 in the NC group. Subgroups were stratified by age, BMI, and the number of embryos transferred. Results CPR and LBR were comparable between HRT and NC protocols. Patients with BMI >30 showed higher CPR and LBR in the NC group compared to HRT, particularly in double embryo transfers (71.43% vs. 51.28%). Age stratification revealed marginally higher CPR for HRT in patients under 35 years, whereas NC slightly outperformed HRT in patients over 35 years, though results were not statistically significant. BMI analysis demonstrated significant differences, with HRT performing better in BMI 25-29.9 and NC being most effective in BMI >30 (p = 0.042 for CPR). Conclusions Both HRT and NC protocols yielded similar overall outcomes, but personalized strategies based on BMI and age may enhance treatment effectiveness. NC appears advantageous for patients with higher BMI and those opting for double embryo transfer. Further prospective studies are warranted to confirm these findings and optimize patient-specific fertility strategies.