title: Obstetrical and neonatal outcomes from the BEST Trial: single embryo transfer with aneuploidy screening improves outcomes after in vitro fertilization without compromising delivery rates.
abstract: OBJECTIVE
  We sought to determine whether performing elective single embryo transfer (eSET) after trophectoderm biopsy and rapid aneuploidy screening results in improved obstetrical and neonatal outcomes compared with transferring 2 untested embryos.
  
  
  METHODS
  The Blastocyst Euploid Selective Transfer (BEST) Trial enrolled infertile couples with a female partner up to age 42 years who were undergoing in vitro fertilization. They were randomized to receive transfer of a single euploid embryo (eSET) or to the standard of care with transfer of 2 embryos that were not biopsied for aneuploidy screening (untested 2-embryo transfer). Gestational age at delivery, birthweight, and neonatal intensive care unit (NICU) lengths of stay were compared with Mann-Whitney U. The risk of preterm delivery, low birthweight, and NICU admission were compared with χ(2).
  
  
  RESULTS
  Among the 175 randomized patients, the delivery rates were similar (69% after euploid eSET vs 72% after untested 2-embryo transfer; P = .6) through the fresh cycle and up to 1 frozen transfer, with a dramatic difference in multiple births (1.6% vs 47%; P < .0001). The risk of preterm delivery (P = .03), low birthweight (P = .002), and NICU admission (P = .04) were significantly higher after untested 2-embryo transfer. Babies born after untested 2-embryo transfer spent >5 times as many days in the NICU (479 vs 93 days; P = .03).
  
  
  CONCLUSIONS
  By enhancing embryo selection with a validated method of aneuploidy screening, a single euploid embryo with high reproductive potential can be selected for transfer. Using this approach, eSET can be performed without compromising delivery rates and improving the chance of having a healthy, term singleton delivery after in vitro fertilization.
authors.affiliation: Reproductive Medicine Associates of New Jersey, Basking Ridge, NJ; Department of Obstetrics, Gynecology, and Reproductive Sciences, Rutgers Robert Wood Johnson Medical School, New Brunswick, NJ. Electronic address: eforman@rmanj.com.
authors.forename: Eric J
authors.initials: EJ
authors.lastname: Forman
authors.affiliation: Reproductive Medicine Associates of New Jersey, Basking Ridge, NJ; Department of Obstetrics, Gynecology, and Reproductive Sciences, Rutgers Robert Wood Johnson Medical School, New Brunswick, NJ.
authors.forename: Kathleen H
authors.initials: KH
authors.lastname: Hong
authors.affiliation: Reproductive Medicine Associates of New Jersey, Basking Ridge, NJ; Department of Obstetrics, Gynecology, and Reproductive Sciences, Rutgers Robert Wood Johnson Medical School, New Brunswick, NJ.
authors.forename: Jason M
authors.initials: JM
authors.lastname: Franasiak
authors.affiliation: Reproductive Medicine Associates of New Jersey, Basking Ridge, NJ; Department of Obstetrics, Gynecology, and Reproductive Sciences, Rutgers Robert Wood Johnson Medical School, New Brunswick, NJ.
authors.forename: Richard T
authors.initials: RT
authors.lastname: Scott
mesh_terms: D000328:Adult; D000782:Aneuploidy; D001724:Birth Weight; D025063:Chromosome Disorders / Q000175:diagnosis*; D005260:Female; D005307:Fertilization in Vitro; D005820:Genetic Testing / Q000379:methods; D006801:Humans; D007231:Infant, Newborn; D011247:Pregnancy; D011256:Pregnancy Outcome; D019836:Preimplantation Diagnosis / Q000379:methods; D056826:Single Embryo Transfer
keywords: aneuploidy screening; in vitro fertilization; preimplantation genetic screening; single embryo transfer