title: Determinants of infant growth in four age windows: a twin study.
abstract: OBJECTIVE
  To identify determinants of growth during infancy.
  
  
  METHODS
  The sample included 424 twin pairs from the East Flanders Prospective Twin Survey. Multilevel regression analysis was performed and intrapair growth correlations were calculated. The main outcome measure was growth, measured in g/kg/d (0-1 month) or in change in weight z-score (0-6, 6-12 and 12-24 months).
  
  
  RESULTS
  Growth during infancy was associated with birth weight and gestational age. One z-score increase in birth weight resulted in -1.77 g/kg/d less growth from 0-1 month (P < .0001). The effect size decreased with age until -0.02 (P = .70) z-scores less growth from 12 to 24 months. Corresponding numbers for one z-score increase in gestational age decreased from 0.78 (P = .001) to 0.06 (P = .40). From 12 to 24 months, paternal height had a significant positive effect. The difference in growth similarity within the twin pair between monozygotic and dizygotic twins increased from non-significant from 0 to 1 month (P = .49) to a monozygotic:dizygotic ratio approximating 2:1 from 12 to 24 months (P = .002).
  
  
  CONCLUSIONS
  From 0 to 1 month, environmental factors are most important for growth, whereas genetic factors become more important over time. This is a first step in identifying age windows for future counseling and interventions on the effects of accelerated growth.
authors.affiliation: Department of Pediatrics, Maastricht University Medical Centre, Maastricht, The Netherlands. bob.touwslager@mumc.nl
authors.forename: Robbert N H
authors.initials: RN
authors.lastname: Touwslager
authors.forename: Marij
authors.initials: M
authors.lastname: Gielen
authors.forename: Catherine
authors.initials: C
authors.lastname: Derom
authors.forename: Antonius L M
authors.initials: AL
authors.lastname: Mulder
authors.forename: Willem-Jan M
authors.initials: WJ
authors.lastname: Gerver
authors.forename: Luc J
authors.initials: LJ
authors.lastname: Zimmermann
authors.forename: Alfons J H M
authors.initials: AJ
authors.lastname: Houben
authors.forename: Coen D A
authors.initials: CD
authors.lastname: Stehouwer
authors.forename: Robert
authors.initials: R
authors.lastname: Vlietinck
authors.forename: Ruth J F
authors.initials: RJ
authors.lastname: Loos
authors.forename: Maurice P
authors.initials: MP
authors.lastname: Zeegers
mesh_terms: D001724:Birth Weight / Q000502:physiology; D001827:Body Height; D016640:Diabetes, Gestational / Q000503:physiopathology; D005220:Fathers; D005260:Female; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D015999:Multivariate Analysis; D011247:Pregnancy; D014429:Twins, Dizygotic / Q000502:physiology*; D014430:Twins, Monozygotic / Q000502:physiology*