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-Müllerian 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.