The incidence of multiple gestations after in vitro fertilization is dependent on the number of embryos transferred and maternal age

Objective: To determine if the incidence of multiple gestations after IVF differs significantly depending on the number of embryos transferred and maternal age. Design: Retrospective analysis of IVF database. Setting: Tertiary care academic center. Patients: One thousand eight hundred sixty- seven patients undergoing IVF with up to four embryos transferred during 1986 through 1993. Main Outcome Measures: The rate of singleton and multiple gestations >20 weeks estimated gestational age (EGA). Results: The incidence of triplet gestations >20 weeks EGA among patients ≤34 years of age with three versus four embryos transferred was 0.3% (1/335) versus 2.4% (15/662), respectively. The incidence of twin gestations >20 weeks EGA among patients ≤34 years of age with two versus four embryos transferred was 1.3% (3/234) versus 7.4% (46/622), respectively. Also among patients ≤34 years of age, the incidence of singleton gestations >20 weeks EGA with two versus three embryos transferred was 12.8% (30/234) versus 15.8% (53/335); with two versus four embryos was 12.8% (30/234) versus 17.2% (107/622); and with three versus four embryos was 15.8% (53/335) versus 17.2% (107/622), respectively. Conclusions: In women ≤34 years of age undergoing IVF-ET, the transfer of four versus three and four versus two embryos significantly increased the incidence of triplet and twin gestations, respectively, without significantly improving the chance of singleton conception. This implies that a policy of transferring only three embryos should be considered in this age group (realizing that such a policy may merit modulation if pretransfer embryo selection is used.)