title: Late-preterm birth and its association with cognitive and socioemotional outcomes at 6 years of age.
abstract: BACKGROUND
  Late-preterm birth (34-36 weeks' gestation) has been associated with a risk for long-term cognitive and socioemotional problems. However, many studies have not incorporated measures of important contributors to these outcomes, and it is unclear whether effects attributed to gestational age are separate from fetal growth or its proxy, birth weight for gestational age.
  
  
  METHODS
  Data came from a study of low- and normal-weight births sampled from urban and suburban settings between 1983 and 1985 (low birth weight, n = 473; normal birth weight; n = 350). Random sampling was used to pair singletons born late-preterm with a term counterpart whose birth weight z score was within 0.1 SD of his or her match (n = 168 pairs). With random-effects models, we evaluated whether pairs differed in their IQ scores and teacher-reported behavioral problems at the age of 6 years.
  
  
  RESULTS
  In adjusted models, late-preterm birth was associated with an increased risk of full-scale (adjusted odds ratio [aOR]: 2.35 [95% confidence interval (CI): 1.20-4.61]) and performance (aOR: 2.04 [95% CI: 1.09-3.82]) IQ scores below 85. Late-preterm birth was associated with higher levels of internalizing and attention problems, findings that were replicated in models that used thresholds marking borderline or clinically significant problems (aOR: 2.35 [95% CI: 1.28-4.32] and 1.76 [95% CI: 1.04-3.0], respectively).
  
  
  CONCLUSIONS
  Late-preterm birth is associated with behavioral problems and lower IQ at the age of 6, independent of maternal IQ, residential setting, and sociodemographics. Future research is needed to investigate whether these findings result from a reduction in gestational length, in utero (eg, obstetric complications) or ex-utero (eg, neonatal complications) factors marked by late-preterm birth, or some combination of these factors.
authors.affiliation: Department of Epidemiology, Michigan State University, B601 West Fee Hall, East Lansing, MI 48824, USA. ntalge@epi.msu.edu
authors.forename: Nicole M
authors.initials: NM
authors.lastname: Talge
authors.forename: Claudia
authors.initials: C
authors.lastname: Holzman
authors.forename: Jianling
authors.initials: J
authors.lastname: Wang
authors.forename: Victoria
authors.initials: V
authors.lastname: Lucia
authors.forename: Joseph
authors.initials: J
authors.lastname: Gardiner
authors.forename: Naomi
authors.initials: N
authors.lastname: Breslau
mesh_terms: D002648:Child; D002657:Child Development; D002675:Child, Preschool; D003072:Cognition Disorders / Q000453:epidemiology / Q000209:etiology*; D016001:Confidence Intervals; D005260:Female; D005500:Follow-Up Studies; D005865:Gestational Age; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D016017:Odds Ratio; D047928:Premature Birth; D012189:Retrospective Studies; D012307:Risk Factors; D012920:Social Behavior Disorders / Q000453:epidemiology / Q000209:etiology*; D012959:Socioeconomic Factors; D013997:Time Factors; D014481:United States / Q000453:epidemiology