Is it justified to transfer two embryos in oocyte donation? A pilot randomized clinical trial.

Multiple pregnancies involve high obstetric and perinatal risks. The aim of this study is to evaluate, in a pilot randomized control study, if the cumulative pregnancy and live birth rates of elective single embryo transfer (eSET) are comparable to the ones obtained with elective double embryo transfer (eDET). A total of 65 patients with at least two good quality embryos was randomized, 34 (52.3%) assigned to the eSET group and 31 (47.7%) to the eDET group. The cumulative pregnancy rates (eSET: 73.5% and eDET: 77.4%. RR: 0.95 95% CI: 0.72-1.25) and live birth rates (eSET: 58.8% and eDET: 61.3%. RR: 0.96 95% CI: 0.64-1.42) were similar in the two groups. The twin pregnancy rate in the fresh transfers of eDET group was 47.7% and 0% in the eSET group. The medical team decided to interrupt the study for reasons related to risks associated with elevated twin pregnancy rate, leaving low numbers of patients within the study as a result. When considering cumulative success rates, eSET and eDET are similar in terms of efficacy. However, eDET involves an increased and unacceptable twin pregnancy rate. The only prevention strategy is single embryo transfer.