Elective single embryo transfer versus double embryo transfer in assisted reproduction

High numbers of embryos transferred during assisted reproduction have become implicated as the cause of higher than normal twinning and multiple gestation rates following this form of therapy. However, reducing the number to a single embryo transferred has been shown to carry unfavourable results in the first cycle, but with similar cumulative live birth rates. This study tested the theory by performing a randomized controlled trial of elective single embryo transfer (SET) versus double embryo transfer (DET) in young women, and follow them up for 1 year to determine the result of cryo-embryo transfer cycles in the two cohorts. The results showed that the probability of a live birth was not significantly different between the two groups, but with a higher rate of twins in the DET group. In addition, during the 1-year follow-up period, the live birth, clinical pregnancy and multiple pregnancy rates were also similar, and in line with the results of the randomized trial. In conclusion, the results of this prospective randomized trial and 1-year follow-up show that in young women, elective SET should be the first line of choice. Even so, these results should be confirmed by larger randomized studies.