© 2008 American Thoracic Society
Is Reverse Causation Responsible for the Link between Duration of Breastfeeding and Childhood Asthma?From the Authors:We thank Dr. Lodge and colleagues for their interest in our article (1). We agree that it is possible that allergic disease in children may influence the duration of breastfeeding. In our article, the analysis of the association of early infant feeding and lung function that was stratified by maternal history of allergy or asthma included physician diagnosed eczema in the first 2 years of life as a covariate. As detailed on p. 845 of the article, "The observed decrease in FEV1/FVC ratio with maternal asthma did not change ... when adjusted by eczema in the child (data not shown)." However, this did not address whether maternal feeding practices might be altered by the child's early development of allergic symptoms. To explore this question, we assessed the relation between eczema in the first 4 months of life and infant feeding in early life (formula introduction before 2 mo, at 2 to less than 4 mo, or at 4 mo or more), and found no relation (P = 0.8). There was also no significant difference in total IgE measured at 9 months between any of the infant feeding groups (P = 0.8). Of interest, children of mothers with asthma were no more likely to be in the longer breastfed group than children of mothers without asthma (30 vs. 28%, respectively). Thus, feeding behavior in this population appears to be unrelated to either the development of allergic symptoms in the child or maternal asthma, indicating that relations between infant feeding and airflows later in life are not affected by the early allergic status of the child.
University of Arizona
University of Arizona FOOTNOTES Conflict of Interest Statement: T.G. received $3,500 in 2008, $9,000 in 2007, $9,500 in 2006, and $8,000 in 2005 for serving on an advisory board, consulting on designing clinical trials, and speaking at conferences sponsored by GlaxoSmithKline; she received $15,000 in 2007, $13,000 in 2006, and $2,500 in 2005, for consulting on slide design and speaking at conferences sponsored by AstraZeneca; she received $2,500 in 2008 and $1,500 in 2005 for serving on an advisory board or speaking at a teleconference sponsored by Novartis; she participated as a speaker in CME-accredited courses sponsored by SOMA Medical Education and Peer Point Medical Education Institute. D.S. has no financial relationship with a commercial entity that has an interest in the subject of this manuscript. A.W. has no financial relationship with a commercial entity that has an interest in the subject of this manuscript. REFERENCES
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