Elective single embryo transfer- the power of one.

Despite the highest historical live birth success rates for couples undergoing in vitro fertilization (IVF), there has been an epidemic of iatrogenic twin and higher order gestation conceived from this treatment. Continued improvement in cryopreservation techniques have allowed preservation of supernumerary embryos for use in future cycles, and refinements in culture systems and embryo selection have resulted in the transfer of fewer embryos while maintaining favorable pregnancy rates. The voluntary transfer of a single high quality embryo, elective single embryo transfer (eSET), has significantly reduced multiple gestation rates and maximized the rate of singleton pregnancy without compromising overall success rates. Although eSET is the standard of care in several developed countries, utilization in the United States has been slow. States with mandated IVF insurance have seen decreases in preterm birth rates yielding down stream health care savings. Herein, the evolution and future applications of this practice to reduce the risk of iatrogenic twins is reviewed.