Breastfeeding is associated with reduced risk of infections at age 6 years

Background: Previous studies have shown that breastfeeding is associated with significant reductions in the risk of common infections among infants in developed countries; however, whether breastfeeding confers longer-term protection against infections is unknown. Methods: We linked data from the 2005-2006 Infant Feeding Practices Study-II and 2012 follow-up data collected when children were 6 years old. We used multivariate logistic regression, controlling for sociodemographics, to examine associations of any and exclusive breastfeeding duration and breastmilk intensity (categorized by tertiles of the percentage of milk feedings being breastmilk from age 0-6 months) with maternal reports of past-year infection (ear, sinus, throat, pneumonia/lung, urinary, cold/upper respiratory) among the 6-year-old children. Results: Among 1,292 respondents with complete data, the most common past-year infections at age 6 years were colds/upper respiratory (66%), ear (25%), and throat (24%) infections. No associations were found among breastfeeding and lung, urinary tract, or cold/respiratory infections. Prevalence of ear, sinus, and throat infections differed by breastfeeding duration, exclusivity, and breastmilk intensity (p<.02 for each). Children who were exclusively breastfed at least 6 months had lower odds of past-year sinus (adjusted odds ratio [AOR]=0.12, 95% confidence interval [95%CI]: 0.02-0.87), throat (AOR=0.20, 95%CI: 0.06-0.64), and ear (AOR=0.34, 95%CI: 0.13-0.89) infections versus those exclusively breastfed <4 months. Breastfeeding duration of ³6 months was associated with significantly reduced odds of the same infections. High breast milk intensity (>66.6% of child's milk feedings from 0-6 months were breastmilk) was associated with lower odds of sinus and throat infections. Conclusions: This is the first study of long-term associations of breastfeeding intensity, exclusivity, and duration, and infections in 6-year-old children in the U.S. The findings suggest that breastfeeding may protect against infection well beyond infancy. We will share some other important ways linked IFPS-II and follow-up study data can be used to examine longer-term, breastfeeding-related outcomes.