In-vitro fertilisation and risk of multiple pregnancy.

There is concern about the medical, social, and economic consequences of multiple pregnancy after in-vitro fertilisation (IVF). The most effective way to limit the risk of such a pregnancy is to replace only one or two embryos simultaneously. This strategy, however, is thought to reduce pregnancy rates. We analysed the rates of multiple pregnancies and live-births in all clinics in the UK in relation to their elective two-embryo transfer (ETT) policies. Our results suggest that replacement of two embryos eliminates the chance of triplets without affecting overall success rates.