Replacement of one selected embryo is just as successful as two embryo transfer, without the risk of twin pregnancy.

The transition of in vitro fertilization from research to standard clinical practice has, to a great extent, been as a result of the use of controlled ovarian hyper stimulation. A disadvantage of the availability of multiple embryos has been the replacement of several embryos leading to an epidemic of multiple pregnancies. This retrospective review of 2606 fresh embryo transfers between 2001 and 2003, where either one or two selected embryos were replaced from an available cohort of at least four, shows that single embryo transfers have a similar pregnancy rate without the risk of multiple pregnancy.