Establishment of criteria for elective single embryo transfer at day 2 or day 3 by analyzing cases with successful implantation of all embryos transferred

Aim: Elective transfer of two good-quality embryos has been used to avoid triplet or high-order multiple pregnancies. However, the rate of twin pregnancies has remained fairly unchanged. In the present study, criteria for elective single embryo transfer (eSET) at day 2 or day 3 were established by analyzing cases with successful implantation of all embryos transferred. Methods: A total of 685 fresh or frozen-thawed embryo transfers following in vitro fertilization/intracytoplasmic sperm injection between April 2002 and March 2006 were performed. Only embryo transfers at day 2 or day 3, but not at blastocyst stage, were included. Successful implantation of all embryos transferred was obtained in 17 pregnancy cycles. Results: Thirty-one gestational sacs with fetal heartbeats were obtained by a total of 31 embryo transfers in 17 infertile women. The average age was 32.6 years (23–38), and 14 (82.3%) of the 17 women were