Single-blastocyst transfer decreases twin gestation without affecting pregnancy outcome.

OBJECTIVE: To compare the respective pregnancy outcomes of cycles undergoing fresh elective single-blastocyst transfer (eSBT) and double-blastocyst transfer (DBT) after IVF.
DESIGN: Retrospective medical record review.
SETTING: Academic medical center. PATIENT(S): Couples undergoing fresh blastocyst transfer after IVF. INTERVENTION(S): One thousand, four hundred, ninety-nine consecutive IVF cycles from January 1, 2002 through March 31, 2006 at the Massachusetts General Hospital Fertility Center were reviewed. Patients undergoing fresh blastocyst transfer (eSBT, n = 52; DBT, n = 187) were identified. MAIN OUTCOME MEASURE(S): Respective pregnancy outcomes and the trend in twin gestations in all cycles undergoing blastocyst transfer, before and after the introduction of the eSBT program. RESULT(S): Statistically similar rates of biochemical pregnancy (76.9% vs. 77.6%), clinical pregnancy (61% vs. 63.4%), live birth (53.8% vs. 54.4%), and pregnancy loss (20% vs. 18.6%) per embryo transfer were observed for fresh eSBT and DBT cycles, respectively. Twin rates for eSBT were statistically significantly lower than for DBT cycles (3.1% vs. 51%). Fresh eSBT and DBT cryopreserved 2.8 vs. 1.7 blastocysts per cycle, respectively. Twenty-four months after the start of eSBT, the twin rate per transfer for all cycles undergoing blastocyst transfer (1, 2, or 3 blastocysts) was statistically significantly reduced from 47.2% to 22.9%, whereas the twin rate per transfer for all embryo transfers in women younger than 35 years of age was statistically significantly reduced from 28.8% to 15.6%. CONCLUSION(S): Given the promising potential of eSBT to markedly reduce the risk of twin gestation without a significant compromise to pregnancy outcomes, an active attempt should be made to consider and use eSBT in the young, favorable-prognosis patient who has good-quality embryos available for transfer and cryopreservation.