Exclusive breastfeeding during the first 3 months of life was associated with significant reduction in respiratory allergies among children at age 6, according to a longitudinal study.

Analysis of data from 1,177 mother-child pairs in the Infant Feeding Practices Study II (IFPS II) demonstrated that 6-year-olds who were exclusively breastfed were 23% less likely than those exclusively formula fed during the first 3 months of life to have been diagnosed with respiratory allergies (adjusted relative risk 0.77, 95% CI 0.61-0.97), reported Galya Bigman, MD, of the University of Maryland at Baltimore.

Exclusive early breastfeeding was also associated with a significantly lower risk for school-age asthma, but only among children with no family predisposition to asthma, she stated in Acta Paediatrica.

“Based on this study, it appears that for children with a genetic predisposition to develop asthma, breastfeeding will not be beneficial in terms of reducing asthma risk,” Bigman told MedPage Today.

She added that another important study finding was that non-exclusive breastfeeding during the first 3 months of life appeared to be insufficient to reduce the risk for respiratory allergies or asthma at age 6.

Around one in 10 children in the U.S have respiratory allergies and one in 14 have asthma, according to recent CDC figures.

While many previous studies have suggested a protective benefit for breastfeeding in reducing asthma risk, most have looked only at never breastfeeding versus ever breastfeeding with a retrospective design, Bigman said, adding that there has also been little previous research examining the impact of breastfeeding on the development of respiratory allergies.

The current study involved analysis of data from IFPS II gathered in 2005-2007, and the subsequent Year 6 Follow-Up (Y6FU) Study in 2012, which was conducted when the children were age 6.

As part of the initial study, the mothers reported their breastfeeding practices on a monthly basis for their child’s first year of life. Asthma and allergy prevalence at age 6 were addressed in the Y6FU survey.

Just under a third of the 1,177 children in the study were exclusively breastfed for the first 3 months of life (32.9%) and by the age of 6, 20.8% had been diagnosed with respiratory allergies, and 11.3% with asthma.

Children exclusively breastfed for 3 months had the fewest respiratory allergies, asthma, and allergic asthma (17.8%, 8.3% and 5.0%, respectively) among the cohort and children who were exclusively formula fed had the highest percentage of respiratory allergies, asthma, and allergic asthma (24.1%, 13.1% and 9.0%, respectively).

Bigman also found that exclusive breastfeeding was associated with a decreased risk of respiratory allergies in both crude (RR 0.80, 95% CI 0.65-0.99) and adjusted (RR 0.77, 95% CI 0.61-0.97) analyses. Exclusive breastfeeding was associated with decreased risk of asthma in the crude analysis (RR 0.77, 95% CI 0.59-0.99).

There were no significant differences in the risks of having asthma or respiratory allergies between children who were breastfed, but not exclusively, and those who only received formula, and infant feeding practices showed no associations with allergic asthma and current asthma in either the crude or adjusted analyses.

Exclusive breastfeeding was linked with less asthma in children without a family history of asthma, but not in children with a family history (adjusted RR 0.66, 95% CI 0.44-0.98).

“Although a number of systematic reviews and meta-analyses showed a moderate beneficial effect of breastfeeding on asthma, half of the reviewed studies did not include a family history of asthma,” Bigman wrote. “Others did not include critical confounders, and most studies were limited to never versus ever breastfeeding, and one examined different types of asthma, such as allergic versus non-allergic asthma.”

Bigman told MedPage Today that the current study design is among the most rigorous ever in the U.S. evaluating early, exclusive breast feeding and respiratory allergy risk.