Public Health Nutrition

Biological and behavioural determinants

Infant weight gain, duration of exclusive breast-feeding and childhood BMI – two similar follow-up cohorts

Ingibjorg Gunnarsdottira1 c1, Lene Schack-Nielsena2, Kim Fleischer Michaelsena2, Thorkild IA Sørensena3 and Inga Thorsdottira1 on behalf of the NordNet Study Group

a1 Unit for Nutrition Research, Landspitali-University Hospital & Faculty of Food Science and Nutrition, University of Iceland, Eirikgsgötu 29, 101 Reykjavik, Iceland

a2 Department of Human Nutrition, Centre of Advanced Food Studies, Faculty of Life Sciences, University of Copenhagen, Bülowsvej 17, 1870 Frederiksberg C, Denmark

a3 Institute of Preventive Medicine, Copenhagen University Hospital, Centre for Health and Society, Øster Søgade 18, 1357 Copenhagen K, Denmark


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.

Design 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.

Setting Iceland and Denmark.

Subjects Randomly selected healthy newborns from Denmark (n 85) and Iceland (n 100).

Results Infants exclusively breast-fed for ≤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 ≤2 months compared with those exclusively breast-fed for ≥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.

(Received September 02 2008)

(Accepted March 04 2009)

(Online publication July 17 2009)


c1 Corresponding author: Email