Five-years of a mandatory single-embryo transfer (mSET) policy dramatically reduces twinning rate without lowering pregnancy rates

Objective: To report the outcomes of a program policy instituted in 2004 mandating single-embryo transfer (mSET) for all women aged < 38 years, with at least seven zygotes, no prior failed fresh cycle at our center, and at least one good-quality blastocyst. Design: Retrospective cohort study. Setting: Academic medical center. Patient(s): All women < 38 years old undergoing a fresh cycle with autologous oocytes and all women undergoing a fresh cycle with donor oocytes from June 1, 1999, to May 31, 2004 (before mSET) and from June 1, 2004, to May 31, 2009 (after mSET). Intervention(s): mSET policy implementation. Main Outcome Measure(s): Live-birth rate, multiple pregnancy rate, clinical volume, and outcomes of all mSET fresh IVF transfers were analyzed. Result(s): Clinical volume was unchanged between the two time groups. After implementation of mSET, live-birth rates improved from 51.1% to 55.9% and multiple-birth rates dropped from 34.8% to 17.5%. A total of 364 mSET fresh transfers were performed with a live-birth rate of 64.6% and a multiple-birth rate of 3.4%. Conclusion(s): A mandatory SET policy based on prognostic factors can be instituted with no drop in clinical volume and no negative effect on delivery rates. Multiple gestation rates can be dramatically lowered. (Fertil Steril (R) 2011; 96: 1367-9. (c) 2011 by American Society for Reproductive Medicine.)