BACKGROUND

Previous studies have shown that breastfeeding is associated with reductions in the risk of common infections among infants; however, whether breastfeeding confers longer term protection is inconclusive.

METHODS

We linked data from the 2005-2007 IFPS II (Infant Feeding Practices Study II) and follow-up data collected when the children were 6 years old. Multivariable logistic regression was used, controlling for sociodemographic variables, to examine associations of initiation, duration, exclusivity of breastfeeding, timing of supplementing breastfeeding with formula, and breast milk intensity (proportion of milk feedings that were breast milk from age 0-6 months) with maternal reports of infection (cold/upper respiratory tract, ear, throat, sinus, pneumonia/lung, and urinary) and sick visits in the past year among 6-year-olds (N = 1281).

RESULTS

The most common past-year infections were colds/upper respiratory tract (66%), ear (25%), and throat (24%) infections. No associations were found between breastfeeding and colds/upper respiratory tract, lung, or urinary tract infections. Prevalence of ear, throat, and sinus infections and number of sick visits differed according to breastfeeding duration, exclusivity, and timing of supplementing breastfeeding with formula (P < .05). Among children ever breastfed, children breastfed for ≥9 months had lower odds of past-year ear (adjusted odds ratio [aOR]: 0.69 [95% confidence interval (95% CI): 0.48-0.98]), throat (aOR: 0.68 [95% CI: 0.47-0.98]), and sinus (aOR: 0.47 [95% CI: 0.30-0.72]) infections compared with those breastfed >0 to <3 months. High breast milk intensity (>66.6%) during the first 6 months was associated with lower odds of sinus infection compared with low breast milk intensity (<33.3%) (aOR: 0.53 [95% CI: 0.35-0.79]).

CONCLUSIONS

This prospective longitudinal study suggests that breastfeeding may protect against ear, throat, and sinus infections well beyond infancy.