title: Assisted reproductive technology and perinatal outcomes: conventional versus discordant-sibling design.
abstract: OBJECTIVE
  To compare risks of adverse perinatal outcomes between assisted reproductive technology (ART) and naturally conceived singleton births using a dual design approach.
  
  
  METHODS
  Discordant-sibling and conventional cross-sectional general population comparison.
  
  
  METHODS
  Not applicable.
  
  
  METHODS
  All singleton live births, conceived naturally or via ART.
  
  
  METHODS
  None.
  
  
  METHODS
  Birth weight, gestational age, low birth weight, preterm delivery, small for gestational age (SGA), low Apgar score.
  
  
  RESULTS
  A total of 32,762 (0.8%) of 3,896,242 singleton live births in the three states were conceived via ART. In 6,458 sibling pairs, ART-conceived singletons were 33 g lighter (adjusted β = -33.40, 95% confidence interval [CI], -48.60, -18.21) and born half a day sooner (β = -0.58, 95% CI, -1.02, -0.14) than singletons conceived naturally. The absolute risk of low birth weight and preterm birth was 6.8% and 9.7%, respectively, in the ART group and 4.9% and 7.9%, respectively, in the non-ART group. The odds of low birth weight were 33% higher (adjusted odds ratio [aOR] = 1.33; 95% CI, 1.13, 1.56) and 20% higher for preterm birth (aOR = 1.20; 95% CI, 1.07, 1.34). The odds of SGA and low Apgar score were not significantly different in both groups (aOR = 1.22; 95% CI, 0.88, 1.68; and aOR = 0.75; 95% CI, 0.54, 1.05, respectively). Results of conventional analyses were similar, although the magnitude of risk was higher for preterm birth (aOR, 1.51; 95% CI 1.46, 1.56).
  
  
  CONCLUSIONS
  Despite some inflated risks in the general population comparison, ART remained associated with an increased likelihood of low birth weight and preterm birth when underlying maternal factors were kept constant using discordant-sibling comparison.
authors.affiliation: Division of Reproductive Health, Centers for Disease Control and Prevention, Atlanta, Georgia; Division of Epidemiology and Public Health, University of Nottingham, Nottingham, United Kingdom; Diabetes Research Centre, University of Leicester, Leicester General Hospital, Leicester, United Kingdom. Electronic address: nnd2@le.ac.uk.
authors.forename: Nafeesa N
authors.initials: NN
authors.lastname: Dhalwani
authors.affiliation: Division of Reproductive Health, Centers for Disease Control and Prevention, Atlanta, Georgia.
authors.forename: Sheree L
authors.initials: SL
authors.lastname: Boulet
authors.affiliation: Division of Reproductive Health, Centers for Disease Control and Prevention, Atlanta, Georgia.
authors.forename: Dmitry M
authors.initials: DM
authors.lastname: Kissin
authors.affiliation: Division of Reproductive Health, Centers for Disease Control and Prevention, Atlanta, Georgia.
authors.forename: Yujia
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Michigan Department of Health and Human Services, Lansing, Michigan.
authors.forename: Patricia
authors.initials: P
authors.lastname: McKane
authors.affiliation: Florida Department of Health, Tallahassee, Florida.
authors.forename: Marie A
authors.initials: MA
authors.lastname: Bailey
authors.affiliation: Massachusetts Department of Public Health, Boston, Massachusetts.
authors.forename: Maria-Elena
authors.initials: ME
authors.lastname: Hood
authors.affiliation: Division of Epidemiology and Public Health, University of Nottingham, Nottingham, United Kingdom.
authors.forename: Laila J
authors.initials: LJ
authors.lastname: Tata
mesh_terms: D000328:Adult; D001034:Apgar Score; D001724:Birth Weight; D016009:Chi-Square Distribution; D003430:Cross-Sectional Studies; D005260:Female; D005298:Fertility; D005865:Gestational Age; D006801:Humans; D007230:Infant, Low Birth Weight; D007231:Infant, Newborn; D007236:Infant, Small for Gestational Age; D007246:Infertility / Q000175:diagnosis / Q000503:physiopathology / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D016017:Odds Ratio; D011247:Pregnancy; D011256:Pregnancy Outcome; D047928:Premature Birth / Q000209:etiology; D027724:Reproductive Techniques, Assisted / Q000009:adverse effects*; D018570:Risk Assessment; D012307:Risk Factors; D035781:Siblings; D016896:Treatment Outcome; D014481:United States; D055815:Young Adult
keywords: Assisted reproductive technology; discordant-sibling design; low birth weight; preterm birth; small for gestational age