title: Infant weight gain, duration of exclusive breast-feeding and childhood BMI - two similar follow-up cohorts.
abstract: OBJECTIVE
  To describe the association between duration of exclusive breast-feeding (EBF), weight gain in infancy and childhood BMI in two populations with a long duration of EBF.
  
  
  METHODS
  Cohort study with follow-up in childhood. Breast-feeding status was reported monthly during infancy. Weight and length were measured at birth, 2, 6 and 12 months of age, as well as in childhood at 6 or 10 years of age.
  
  
  METHODS
  Iceland and Denmark.
  
  
  METHODS
  Randomly selected healthy newborns from Denmark (n 85) and Iceland (n 100).
  
  
  RESULTS
  Infants exclusively breast-fed for < or =2 months gained 348 (95% CI 69, 626) g more weight from 2 to 6 months than infants exclusively breast-fed for 3-4 months (P = 0.009). Weight gain from 6 to 12 months was found to be greater among infants exclusively breast-fed for < or =2 months compared with those exclusively breast-fed for > or =5 months (P = 0.008). A greater weight change, in terms of Z-score, between the ages of 2 and 6 months was associated with higher Z-score of childhood BMI, adjusted for birth weight, country and duration of EBF (B = 0.49, se = 0.11, P < 0.001, adj. R2 = 0.15). However, the association was much stronger in the Icelandic cohort than the Danish one.
  
  
  CONCLUSIONS
  Although duration of EBF was not associated with childhood BMI in the present study it may modulate growth rate in infancy, which is related to childhood BMI. However, other factors determinative for infant growth also need to be considered when assessing the relationship of early growth and nutrition to childhood overweight, as traditions in complementary food might differ between populations.
authors.affiliation: Unit for Nutrition Research, Landspitali-University Hospital & Faculty of Food Science and Nutrition, University of Iceland, Eirikgsgötu 29, 101 Reykjavik, Iceland. ingathor@landspitali.is
authors.forename: Ingibjorg
authors.initials: I
authors.lastname: Gunnarsdottir
authors.forename: Lene
authors.initials: L
authors.lastname: Schack-Nielsen
authors.forename: Kim Fleischer
authors.initials: KF
authors.lastname: Michaelsen
authors.forename: Thorkild I A
authors.initials: TI
authors.lastname: Sørensen
authors.forename: Inga
authors.initials: I
authors.lastname: Thorsdottir
mesh_terms: D015992:Body Mass Index; D001942:Breast Feeding / Q000706:statistics & numerical data*; D002648:Child; D002657:Child Development / Q000502:physiology*; D002675:Child, Preschool; D015331:Cohort Studies; D003718:Denmark; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007055:Iceland; D007223:Infant; D041943:Infant Formula / Q000706:statistics & numerical data*; D007227:Infant Nutritional Physiological Phenomena / Q000502:physiology*; D007231:Infant, Newborn; D008297:Male; D050177:Overweight / Q000453:epidemiology / Q000209:etiology; D013997:Time Factors; D015430:Weight Gain