Mersereau J, et al. - The factors related to high live birth rate and low multiple birth rate in fresh and frozen-thawed assisted reproductive technology (ART) cycles are examined in this study. The outcome of the current study reports a 10%-15% reduction in live birth rate and a 47% decrement in multiple birth rate with single embryo transfer (SET) compared with double embryo transfer (DET) in the setting of favorable patient prognostic factors. These outcomes present an opportunity to increase the rate of SET across the United States and thereby decrease the multiple birth rate and related poor perinatal outcomes with assisted reproductive technology pregnancies.