1. Single embryo transfer of pre-screened euploid embryos resulted in similar delivery rates as traditional transfer of multiple untested embryos.
2. Single euploid embryo transfers were associated with fewer multiple births and better neonatal safety outcomes.
Evidence Rating Level: 1 (Excellent)
Study Rundown: In this study, researchers found that IVF with a single, genetically pre-screened embryo resulted in similar delivery rates with fewer multiple births, preterm deliveries, and NICU admissions than with multiple embryo transfer. This study suggests that the addition of comprehensive chromosome screening to single embryo transfer can improve safety outcomes without altering success rates.
This is one of the first studies evaluating a potential method to maintain high success rates while decreasing risk of multiple gestation in ART. A strength of this study is the randomized, controlled design. Limitations include small sample size, lack of cost analysis and inclusion of only those patients who are best candidates for single embryo transfer: healthy patients with normal ovarian reserve, BMI, and endometrial. Future studies might investigate outcomes in a broader ART patient population and also investigate cost-benefit of genetic prescreening.
Relevant Reading: CDC National Summary Report: Assisted Reproductive Technology (ART)
Study author, Eric Forman, M.D., attending physician and faculty at Reproductive Medicine Associates of New Jersey and Rutgers Robert Wood Johnson Medical School, New Brunswick, NJ, talks to 2 Minute Medicine:
“Multiple gestation resulting from assisted reproductive technologies (ART) is a burden on patients, clinicians and the health care system. The BEST trial shows that by performing Comprehensive Chromosome Screening and selecting one genetically normal embryo over multiple unscreened embryos, we have the potential to alter the clinical paradigm of IVF [by] improving safety without significantly diminishing success rates.”
In-Depth [randomized controlled trial]: Researchers randomized 175 women receiving IVF to a single embryo transfer of an euploid embryo that underwent comprehensive chromosomal screening (n=89), or multiple embryo transfer of two embryos untested for aneuploidy (n=86). The primary outcome was achievement of viable gestation. Secondary outcomes included gestational age at delivery, birth weight, and NICU admissions.
Compared with the control method, transfer of a single euploid embryo resulted in fewer multiple births (1.6% vs. 47%, p<0.0001), as well as lower rates of preterm delivery (13% vs 29%, p=0.03), low birth weight (11% vs 33%, p=0.002), and NICU admissions (11% vs 26%, p=0.04). Babies born after transfer of multiple, un-screened embryos spent more than five times as many days in the NICU as those resulting from single euploid embryo transfers (479 vs 93 days, p=0.03). Cumulative delivery rates were similar between groups (69% vs 72%, p=0.6).
By Maren Shapiro and Leah Hawkins, MD, MPH
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