Date of Defense:
May 3, 2018
Background: Rapid infant weight gain (RIWG), defined as an increase in weight- for-age Z score (WAZ) greater than 0.67, is a strong predictor of childhood obesity. Studies have shown that there is an association between weight gain and infant feeding method. However not many studies have examined these associations by race/ethnicity. Our objective in this study was to test the association of (i) feeding method (ii) duration of breastfeeding as predictors of RIWG among different races/ethnicities.
Methods: Data was obtained from Minnesota Women Infant and Children (WIC) database on subjects born from 2012 to 2015 who were enrolled in Minnesota WIC program. Study subjects included Infants who had data collected at birth and 12 months of age, had been carried to term (37 – 40 weeks) and had normal birth weights (2,500g – 4,000g) (N = 45,981). Feeding methods and breastfeeding duration were modeled using unconditional logistic regression models adjusting for potential confounders.
Results: 29% of infants in our study were classified as having RIWG. The associations of RIWG with breastfeeding history differed by race/ethnicity with breast-fed babies having significantly lower odds when compared to non-breastfed babies of the same race. This was most pronounced amongAmerican Indian infants, where breastfeeding had a strong, negative association with RIWG (OR = 0.570 95% CI = 0.417, 0.778). Association of RIWG and breastfeeding duration also differed by race/ethnicity, babies breast-fed for 6 months or greater had lower odds of RIWG compared with babies breast-fed for less than 3 months in the same race. The association was confounded by maternal pre-pregnancy BMI and smoking status.
Conclusion: This study supports evidence that infancy is a critical period with high susceptibility to become overweight or obese and interventions that encourage breastfeeding in the first year of a child should be emphasized. More studies should be done to examine other factors that predispose to obesity and how these might differ among different races/ethnicities.