Elective single-embryo transfer (eSET) is when a woman undergoing IVF chooses to have a single embryo transferred when multiple embryos are available. The primary goal of eSET is to decrease the rates of multiple pregnancies associated with IVF. Transferring more than one embryo increases the chances of having a multiple pregnancy (twins, triplets, etc.) and the risks that come with it.  Multiple pregnancies often lead to premature delivery. Babies born prematurely are at risk for serious short-term and long-term health problems such as cerebral palsy, long-term lung and gastrointestinal problems, among others.