title: Cognitive ability in adolescents born small for gestational age: Associations with fetal growth velocity, head circumference and postnatal growth.
abstract: BACKGROUND
  Small size at birth may be associated with impaired cognitive ability later in life. The aim of this study was to examine the effect of being born small for gestational age (SGA), with or without intrauterine growth restriction (IUGR) on cognitive ability in late adolescence.
  
  
  METHODS
  A follow-up study of a former cohort included 123 participants (52 males); 47 born SGA and 76 born appropriate for gestational age (AGA). Fetal growth velocity (FGV) was determined by serial ultrasound measurements during the third trimester. A control group matched for age and birthplace was included. The original Wechsler Adult Intelligence Scale (WAIS) was administered, and verbal, performance and full-scale Intelligence Quotient (IQ) scores were calculated.
  
  
  RESULTS
  There was no difference in IQ between adolescents born SGA and AGA. FGV or IUGR during the third trimester did not influence cognitive ability in late adolescence. Full-scale IQ was positively related to head circumference (HC) in adolescence (B: 1.30, 95% CI: 0.32-2.28, p=0.01). HC at birth and three months was positively associated with full-scale IQ. Catch-up growth in the group of SGA children was associated with a significantly increased height, larger HC, increased levels of insulin-like growth factor-I (IGF-I) and increased full-scale IQ compared to those born SGA without catch-up growth.
  
  
  CONCLUSIONS
  SGA and IUGR may not be harmful for adult cognitive ability, at least not in individuals born at near-term. However, known risk factors of impaired fetal growth may explain the link between early growth and cognitive ability in adulthood.
authors.affiliation: Department of Growth and Reproduction, Rigshospitalet, University of Copenhagen, Denmark. Electronic address: rikke.beck@dadlnet.dk.
authors.forename: Rikke Beck
authors.initials: RB
authors.lastname: Jensen
authors.affiliation: Department of Growth and Reproduction, Rigshospitalet, University of Copenhagen, Denmark.
authors.forename: Anders
authors.initials: A
authors.lastname: Juul
authors.affiliation: Department of Gynaecology and Obstetrics, Holbaek Sygehus, Sygehus Vestsjaelland, Denmark.
authors.forename: Torben
authors.initials: T
authors.lastname: Larsen
authors.affiliation: Department of Public Health and Center for Healthy Aging, University of Copenhagen, Denmark.
authors.forename: Erik Lykke
authors.initials: EL
authors.lastname: Mortensen
authors.affiliation: Department of Neonatology, Rigshospitalet, University of Copenhagen, Denmark.
authors.forename: Gorm
authors.initials: G
authors.lastname: Greisen
mesh_terms: D000293:Adolescent; D002657:Child Development / Q000502:physiology*; D003071:Cognition / Q000502:physiology*; D005260:Female; D047109:Fetal Development / Q000502:physiology*; D005500:Follow-Up Studies; D005865:Gestational Age; D006257:Head / Q000033:anatomy & histology*; D006801:Humans; D007231:Infant, Newborn; D007236:Infant, Small for Gestational Age / Q000523:psychology*; D007360:Intelligence / Q000502:physiology*; D008297:Male; D009483:Neuropsychological Tests
keywords: Cognitive ability; Intelligence; Small for gestational age (SGA)