Practice patterns and outcomes with the use of single embryo transfer in the United States

OBJECTIVE: To evaluate factors associated with the use of elective single embryo transfer (eSET) and its effect on assisted reproductive technology (ART) outcome. DESIGN: Historical cohort. SETTING: Clinic-based data. PATIENT(S): A total of 69,028 ART cycles of autologous fresh embryo transfers with additional embryos cryopreserved during the same cycle performed during 2004-06 and reported to the Society for Assisted Reproductive Technology Clinic Outcome Reporting System database. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Factors associated with the number of embryos transferred, and the odds of pregnancy, live birth, and multiple-infant live birth by number of embryos transferred as adjusted odds ratios (AORs). RESULT(S): Single embryo transfer was used more with uterine factor (AOR 1.76) and less with male factor, endometriosis, or tubal factor (AOR 0.81, 0.72, 0.83, respectively). Compared with women aged or =40 years (AOR 0.74 and 0.39, respectively). Compared with White women, eSET was used more with Asian (AOR 1.52) and less with Black or Hispanic women (AOR 0.73 and 0.67, respectively). Compared with eSET, the likelihood of pregnancy, live birth, or multiple-infant live birth was more likely with two embryos (AOR 1.33, 1.34, and 27.4, respectively). CONCLUSION(S): Elective SET, used more for younger women with specific diagnoses, is associated with slightly reduced likelihood of a live birth but much reduced likelihood of multiples.