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 <36 years old. Fifteen (88.2%) of the 17 pregnancies were established at the first attempt of assisted reproductive technology (ART). Of the 17 women, eight (47.1%) women were multigravida and four (23.5%) women were multipara. The indications for ART or insemination methods did not seem to be related to the pregnancy results. Twenty-nine (93.5%) of 31 embryos implanted were considered good-quality embryos. Of the 17 fresh embryos transferred at day 2, 15 were at the 4-cell stage and two were at the 5-cell stage. Of the 11 fresh embryos transferred at day 3, one was at the 6-cell stage, two were at the 7-cell stage and eight were at the 8-cell stage.Conclusion: The criteria for eSET at day 2 or day 3 were established as follows: <36 years of age, a first treatment cycle and more than two good-quality embryos developed at least to the 4-cell stage at day 2, or 6-cell stage at day 3. Additionally, the past history of pregnancy or delivery should be considered, as patients positive for such history might have better implantation ability. eSET can be highly recommended to avoid twin pregnancies in subjects with the established criteria.