Infant milk feeding, infections and allergies in young children

During the first months of life, infant feeding is exclusively milk based. While the protective effect of breastfeeding on childhood infections has been clearly established, particularly in developing countries, the link between breastfeeding and allergies remains more controversial. Moreover, as the duration of breastfeeding is relatively short in France, many infants are exposed to infant formula from the first weeks. Thus, the objectives of my thesis were to study the links between breastfeeding and infections or allergies in childhood in a context of short breastfeeding duration and good hygienic conditions, to describe infant formulas used in the first months of life and to assess whether some components of infant formula were associated with allergic symptoms in the first 2 years of life. Using data from two French birth cohorts, EDEN and ELFE, I was able to show that, despite an unfavorable context, breastfeeding is associated with a lower risk of long duration of hospitalizations for infection, episodes of diarrhea and use of antibiotics in the first few years of life. Weaker associations were also observed between breastfeeding and a lower risk of otitis and respiratory infections in the first 2 years of life and eczema in the 1st year of life. My work has also highlighted the great variety of infant formula consumed by infants who are not exclusively breastfed. No protective effect of infant formula with a “hypoallergenic” label could be found against allergic symptoms up to 2 years. Moreover, a higher risk of wheezing at 1 year in children with a family history of allergy or food allergy at 2 years in children with no family history of allergy was found in children consuming these formulas at 2 months, compared to those consuming a standard infant formula. If my work does not establish a causal link, it emphasizes the need to conduct new randomized trials on relatively large samples to better understand the health impacts of these infant formulas.