The development of assisted reproductive technology (ART) has led to the birth of nearly 6 million children since the first IVF baby in 1978. For many years, it was routine practice to transfer multiple embryos in order to obtain the highest pregnancy rates. This strategy has induced a dramatic increase in multiple pregnancies and the associated complications for the mother and the child. Following better awareness of these issues, ART specialists have tried to reduce multiple pregnancy rates with the goal of producing a single, healthy full term baby. Improvement in embryo culture and cryopreservation are the key factors leading to the strategy of elective single embryo transfer (eSET) which represents the best option to achieving this goal. However eSET strategy needs to be implemented in good prognosis patient with good quality embryos.