We thank Sears et al. for their comments on our annotation.1 They point out that they have never suggested that the children should not be breast-fed on the basis of their findings and neither did we suggest that they had recommended such a course. Indeed, we were well aware of, and referred to, their previous statement on this issue.2 A point of concern is that others who are less well informed might misinterpret the conclusion in their Lancet paper3 that breast-feeding ‘may even increase the risk’ of atopy and asthma. There is considerable community concern concerning allergic disease and such statements have the potential to influence mothers and practitioners to make a decision not to breast-feed. Sears et al. agree that there are protective effects against allergic disease in early life quote, ‘studies with outcomes examined over the first few years of life generally indicate that breast-feeding protects against early childhood wheezing and to some extent atopic dermatitis’. We also agree with their conclusion that breast-feeding has not been shown to have preventative effects on asthma and atopy in later life. Thus, the issue is whether one regards those positive benefits on allergic disease in early life as one rationale for recommending breast-feeding as we have done, or emphasize the lack of a proven protective effect in later life as advocated by Sears et al. It is perhaps not surprising that any benefits from breast-feeding with regard to allergic disease are most prominent in early life as in later life, other environmental considerations come into play. However, a significant issue from their Lancet paper was their suggestion that breast-feeding might increase the risk of atopic disease. This controversial suggestion obviously demands close examination. Sears et al. address possible discrepancies between the data provided in their original Lancet publication3 and that provided on the same cohort in their article in the New England Journal of Medicine.4 The fact remains that the statistic (P for trend) that they chose to examine influences on severity of asthma in the latter publication did not show any adverse effect of breast-feeding. In their list of the independent risk factors for persistent asthma in adulthood, they listed allergy to house dust mites, smoking, airway hyperresponsiveness and female sex but not breast-feeding.4 In this correspondence, they provide additional analysis of their New England Journal of Medicine figures stating that the prevalence of breast-feeding was significantly higher among those with persistent, relapsing or remitting asthma (56.8% vs 48.3%, P = 0.038) at 26 years of age. However, when examining whether breast-feeding protects against or promotes the development of long-term asthma, it seems illogical to include the category of asthma in remission in the persisting category, particularly as from their paper the remission may have occurred from 11 years of age. Examination of their data on the effect of breast-feeding on persisting, relapsing and intermittent asthma as compared to transient asthma never wheezed, and asthma in remission indicates that the prevalence of breast-feeding in the group with ongoing symptoms is 50.7% and in the remission, transient or never wheezed group 52.6% (P = 0.67). On face value this does not support the suggestion that breast-feeding may increase the risk of asthma in adult life. With respect to some of the additional points raised by Sears et al., they again refer to the Tucson cohort,5 which suggests that breast-feeding may exacerbate asthma outcomes in later life, without acknowledging the very small numbers involved. The issue as to whether mothers who have children with atopic eczema in early life, and thus choose to prolong breast-feeding, is not resolved by their statement that ‘as atopic eczema is very rare before age 4 weeks, this should not have impacted the decision to breast-feed’. A recent population-based study indicates that, of those infants who manifest eczema by 6 months of age, eczema was present in 40% at 4 weeks of age.6 The importance of studies such as that of Sears et al., which have examined the long-term influence of breast-feeding on atopic disease, should be acknowledged and we did so in the final paragraph of our annotation.1 However, the suggestion that breast-feeding may increase the risk of atopy or asthma in later life is far from proven.
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Jan 1, 2020
Luana Lopes Padilha + 9
Open Access
