title: Long-term cognitive and school outcomes of late-preterm and early-term births: a systematic review.
abstract: BACKGROUND
  Children born before full term (39-41 weeks' gestation) are at increased risk of adverse cognitive outcomes. Risk quantification is important as late-preterm (LPT; 34-36 weeks) and early-term (ET; 37-38 weeks) births are common.
  
  
  METHODS
  This review analyses the effect of LPT and ET births on long-term cognitive and educational outcomes. The primary outcome was general cognitive ability. Secondary outcomes included verbal/non-verbal intelligence quotient, subject-specific school performance and special educational needs. The search strategy included Medline and Embase from January 1975 to June 2013. Eligible studies investigated specified outcomes and included suitable gestational age participants assessed at 2 years and older. Outcome measures and socio-demographic descriptors were extracted, and data meta-analysed where possible.
  
  
  RESULTS
  Eight studies compared ET birth with full-term birth. Fourteen studies compared LPT birth with either term birth (>37 weeks, n = 12 studies) or full-term birth (39-41 weeks, n = 2 studies). Substantial between-study heterogeneity existed. LPT and ET children underperformed in most outcomes compared with their term/full-term counterparts, respectively. For example, LPT children had an increased risk of lower general cognitive ability (adjusted risk ratio 1.38 [95% confidence interval 1.06-1.79]), and full-term children performed 5% of a standard deviation higher (z-score 0.05 [0.02, 0.08]) than ET children. Poorer outcomes persist into adulthood; term cohorts performed 5% of a standard deviation higher than LPT cohorts (z-score 0.05 [0.04, 0.07]), and full-term cohorts performed 3% of a standard deviation higher than ET cohorts (z-score 0.03 [0.02, 0.04]).
  
  
  CONCLUSIONS
  This review critically examines the knowledge around long-term cognitive outcomes of LPT and ET births, demonstrating multiple, small, adverse differences between LPT/ET and term/full-term births.
authors: National Perinatal Epidemiology Unit, University of Oxford, Oxford, UK.|Royal Children's Hospital, Parkville, Vic., Australia.
authors: E
authors: E
authors: Chan
authors: Monash Lung and Sleep, Monash Medical Centre, Clayton, Vic., Australia.
authors: P
authors: P
authors: Leong
authors: National Perinatal Epidemiology Unit, University of Oxford, Oxford, UK.
authors: R
authors: R
authors: Malouf
authors: National Perinatal Epidemiology Unit, University of Oxford, Oxford, UK.
authors: M A
authors: MA
authors: Quigley
mesh_terms: D002653:Child Behavior Disorders / Q000209:etiology / Q000503:physiopathology / Q000523:psychology*; D002675:Child, Preschool; D003072:Cognition Disorders / Q000209:etiology* / Q000503:physiopathology / Q000523:psychology*; D018479:Early Intervention, Educational / Q000379:methods; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007234:Infant, Premature / Q000523:psychology*; D007235:Infant, Premature, Diseases / Q000209:etiology* / Q000503:physiopathology / Q000523:psychology; D016017:Odds Ratio
keywords: cognitive outcomes; early-term birth; education achievement; general cognitive ability; late-preterm birth; school performance