Effectiveness of elective single versus double frozen embryo transfer in good prognosis in vitro fertilization patients

Objective: This study aimed to evaluate the effectiveness of elective single embryo transfer (eSET) versus double embryo transfer (DET) in frozen embryo transfer cycles following in vitro fertilization (IVF) treatment in good prognosis patients. The outcome would provide medical data for the multiple pregnancy rate reduction in IVF treatment. Methods: This multicenter retrospective cohort study was performed in patients undergoing the first frozen embryo transfer (FET) cycles at IVF centers which belonged to the IVFMD Group, Vietnam, from January 2018 to May 2020. Patients were divided into four groups, based on the number of embryos transferred, as follows: Group 1: one good quality day-3 embryo (eSET D3), Group 2: one good quality day-5 embryo (eSET D5), Group 3: two good quality day-3 embryos (DET D3), and Group 4: two good quality day-5 embryos (DET D5). The primary outcome of the study was live birth rates (LBR) after the first FET. Secondary outcomes were also analyzed, including pregnancy outcomes (beta-hCG positive, clinical pregnancy, miscarriage < 12 weeks, ongoing pregnancy 12 weeks, miscarriage < 20 weeks, and multiple birth rates [MBR]), as well as neonatal outcomes (birth weight and gestational age at birth). Results:There were 819 patients, of which 819 FET cycles were analyzed, including 132 eSET D3, 278 eSET D5, 140 DET D3, and 269 DET D5. LBR and MBR values were significantly lower in the eSET D3 group than in the DET D3 group (LBR: 22.7% vs 39.3%, p = 0.002; MBR: 3.3% vs 29.1%, p < 0.001, respectively). MBR was also significantly lower in eSET D5 compared with DET D5 (9.6% vs 38.3%, p < 0.001), while LBR was comparable between the two groups (41.4% vs 42.8%, p < 0.74). Birth weight and gestational age at birth were similar between eSET and DET, regardless of day-3 or day-5 embryo transfer. Conclusions: Among infertile, good prognosis women undergoing FET, the eSET significantly decreased multiple birth rates compared with double embryo transfer, while still sustaining an acceptable rate of live birth as well as pregnancy and neonatal outcomes.