The Interplay Between Eczema and Breastfeeding Practices May Hide Breastfeeding’s Protective Effect on Childhood Asthma

Abstract

Early allergic disease manifestations in infants may influence breastfeeding practices. In the current study, researchers sought to examine the relationship between breastfeeding duration and the development of asthma and allergic asthma phenotypes, stratified by a diagnosis of eczema during or after breastfeeding.Children who participated in the 6 year follow-up of the HealthNuts study, a population-based, longitudinal cohort study of allergic diseases in Australia.Children were enrolled between the ages of 11 and 15 months, and data regarding breastfeeding history, eczema diagnosis, environmental exposures, and family history of allergic disease were collected via questionnaire. At 6 years, information on wheeze, medication use, and parental report of physician-diagnosed asthma were obtained. Skin-prick testing to foods and aeroallergens at the age of 6 helped to stratify children with asthma into allergic and nonallergic phenotypes. From an original cohort of 5276 children, 3663 had completed questionnaires at 6 years, 3111 underwent skin testing, and 3632 had asthma data available for analysis. Children were characterized as never or ever breastfed. Of those breastfed, exclusive breastfeeding was categorized as never, <6 months, or >6 months. The overall duration of breastfeeding was treated as both a continuous (number of months) and categorical variable (<3 months, 3 to <6 months, 6 to <12 months, or >12 months).Children who did not participate in the full questionnaire at the age of 6 were more likely to be never breastfed, from a lower socioeconomic background, have one or both parents born outside of Australia, have no family history of allergic disease, and have had exposure to prenatal maternal or environmental smoking. Among children with asthma data, 96% were breastfed. At the age of 6, the prevalence of current asthma was 13%. Children with asthma were more likely to be male, have a parental history of asthma, have a family history of allergic disease, have been born preterm, have been born via cesarean delivery, and have been exposed to maternal smoking during pregnancy. Breastfeeding initiation was not associated with current asthma at the age of 6 years (adjusted odds ratio: 0.76) when compared with never breastfeeding. An increased duration of breastfeeding in children without eczema in infancy was associated with a reduced odds of asthma (per month increase; adjusted odds ratio: 0.98), which equates to a 0.86 reduced odds of asthma for a 6 month increase in breastfeeding. This association was not apparent in children who were diagnosed with eczema during breastfeeding.A longer duration of breastfeeding was associated with a reduced odds of asthma at the age pf 6 years among children without history of eczema in the first year. This association was masked before stratification of patients by history of eczema in infancy.Breastfeeding is known to be beneficial for improving many health outcomes. However, previous studies have not clearly demonstrated protective effects for breastfeeding on asthma. In the current study, a modest protective association was observed between an increased duration of breastfeeding and asthma but only among children who were not diagnosed with eczema in their first year. This association is complex because infantile eczema is a known risk factor for asthma and has also been shown to influence breastfeeding choices. Additional study is needed on the interplay between breastfeeding practices, early allergic manifestations, and the risk of subsequent allergic outcomes.