Multiple pregnancies are the most frequent and serious complication of assisted reproduction. Both high-order multiple and twin pregnancies entail a number of medical and economic outcomes that affect the children, the mother, the parents, the families, and society as a whole. Limiting the number of embryos to transfer is the only method available to decrease the incidence of multiple pregnancies. Single Embryo Transfer reviews the advantages and limitations of this approach to assisted reproduction. The crucial issue of selecting the best embryo will be reviewed in detail. All clinical...