In vitro fertilization with single euploid blastocyst transfer: a randomized controlled trial

Objective: To determine whether performing comprehensive chromosome screening (CCS) and transferring a single euploid blastocyst can result in an ongoing pregnancy rate that is equivalent to transferring two untested blastocysts while reducing the risk of multiple gestation. Design: Randomized, noninferiority trial. Setting: Academic center for reproductive medicine. Patient(s): Infertile couples (n = 205) with a female partner less than 43 years old having a serum anti-Mullerian hormone level >= 1.2 ng/mL and day 3 FSH <12 IU/L. Intervention(s): Randomization occurred when at least two blastocysts were suitable for trophectoderm biopsy. The study group (n = 89) had all viable blastocysts biopsied for real-time, polymerase chain reaction-based CCS and single euploid blastocyst transfer. The control group (n = 86) had their two best-quality, untested blastocysts transferred. Main Outcome Measure(s): The ongoing pregnancy rate to >= 24 weeks (primary outcome) and the multiple gestation rate. Result(s): The ongoing pregnancy rate per randomized patient after the first ET was similar between groups (60.7% after single euploid blastocyst transfer vs. 65.1% after untested two-blastocyst transfer; relative risk [RR], 0.9; 95% confidence interval [CI], 0.7-1.2). A difference of greater than 20% in favor of two-blastocyst transfer was excluded. The risk of multiple gestation was reduced after single euploid blastocyst transfer (53.4% to 0%), and patients were nearly twice as likely to have an ongoing singleton pregnancy (60.7% vs. 33.7%; RR, 1.8; 95% CI, 1.3-2.5). Conclusion(s): In women <= 42 years old, transferring a single euploid blastocyst results in ongoing pregnancy rates that are the same as transferring two untested blastocysts while dramatically reducing the risk of twins.