An assessment of alternative policies for embryo transfer in an in vitro fertilization-embryo transfer program.

Conventionally, in in vitro fertilization (IVF) programs, all embryos obtained up to three are freshly transferred in the IVF cycle and supernumerary embryos frozen if cryopreservation facilities exist. This study was concerned with assessing alternative policies for embryo transfer (ET). When three or fewer embryos were obtained in the IVF cycle, fresh embryo transfer was either excluded (group I, n = 69) or only one embryo was immediately transferred (group II, n = 46), the remainder being transferred after freezing and thawing. The pregnancy rate in these two policies was compared to that in a control group of patients (group III, n = 115) in whom all the embryos were transferred in the IVF cycle. The ongoing pregnancy rate was similar in all three groups. No multiple pregnancies occurred in groups I and II compared with one in the controls. The consequences of these policies for pregnancy rates and the incidence of multiple gestation are discussed. It is concluded that the deliberate limitation of fresh ET to a maximum of one embryo followed by one or more cycles of thawed frozen ET is not detrimental to the pregnancy rate and is less likely to be associated with multiple gestations. Conversely, this policy increases the workload of the laboratory staff and raises certain ethical questions.