• American Samoa;
  • breastfeeding;
  • obesity


What is already known about this subject
  • Samoan adults are recognized for their particularly high body mass index and prevalent obesity.
  • While Polynesians are understudied, in other populations infancy is a critical period in the development of obesity.
  • Breastfeeding has been shown to attenuate obesity risk.
What this study adds
  • Samoan infants show remarkably rapid gain in weight but not length in early infancy resulting in a prevalence of overweight and obesity far higher than has been previously reported elsewhere.
  • Breastfeeding is associated with slower weight gain in infancy suggesting that its protective benefits for obesity risk are generalizable outside of European-derived populations.


Samoans are recognized for their particularly high body mass index and prevalent adult obesity but infants are understudied.


To examine the prevalence of overweight and obesity and determine the contribution of feeding mode to obesogenic growth trajectories in American Samoan infants.


Data were extracted from the well baby records of 795 (n = 417 male) Samoan infants aged 0–15 months. Mixed-effects growth models were used to produce individual weight and length curves. Further mixed-effects models were fitted with feeding mode (breastfed, formula- or mixed-fed) as a single observation at age 4 (±2) months. Weight and length values were converted to z-scores according to the Centers for Disease Control 2000 reference.


At 15 months, 23.3% of boys and 16.7% of girls were obese (weight-for-length > 95th percentile). Feeding mode had a significant effect on weight and length trajectories. Formula-fed infants gained weight and length faster than breastfed infants. Formula-fed boys were significantly more likely to be obese at 15 months (38.6%) than breastfed boys (23.4%), χ2 = 8.4, P < 0.01, odds ratio = 2.05, 95% confidence interval (1.04, 4.05).


Obesity in American Samoans is not confined to adults. Obesity prevention efforts should be targeted at early life and promotion of breastfeeding may be a suitable intervention target.