MS 20171226 / Stordal et al - Does longer breastfeeding duration decrease the risk of asthma?

Abstract

There are many well-documented benefits of breastfeeding; however, the effect of breastfeeding in preventing childhood asthma is not clear. As randomized controlled trials on this topic would be unfeasible and unethical to conduct, clinicians must rely on the results of observational studies. However, this question has been difficult to untangle with observational studies, as breastfeeding practices are also confounded by other feeding practices, such as the timing of introducing complementary foods. In addition, large numbers of infants are needed for these studies to control for the many factors (delivery type, gestational age, maternal and paternal history of allergy, etc) that may be also associated with asthma risk. In this volume of The Journal, Størdal et al present the results of a cohort study to determine the association between breastfeeding duration and the risk of childhood asthma, as well as the timing of the introduction of complementary foods and the risk of childhood asthma. They analyzed data from the Norwegian Mother and Child Study, a national prospective cohort study that included prenatal and follow-up data for over 41 000 children up to 7 years of age. Based on the main analysis, the authors found that the timing of complementary food introduction was not associated with the development of asthma. In addition, breastfeeding duration was not associated with the development of asthma. Additional subanalyses were conducted. Only for those low-risk families, where both parents had no history of allergies or asthma, was decreased breastfeeding duration associated with an increased risk of asthma. There are some limitations to this study. The infants were from only one country and the results may not be generalizable to other populations. In addition, the outcome of interest, asthma, was determined at 7 years of age. It is still possible for some of the 7-year-olds in the cohort to develop asthma at a later age. Differences may still develop during the follow-up analyses and there may be still more to learn from this cohort. Nevertheless, the size and scope of this prospective birth cohort study offers a wonderful opportunity to examine the relationship between early infant feeding patterns and risk of childhood asthma. The results suggest no reason to stop championing breastfeeding and encouraging families to breastfeed as long as possible. However, the results of this study suggest that decreasing the risk of childhood asthma by 7 years of age for all children is far from a guaranteed benefit for breastfeeding. At best, we can make only limited statements about longer breastfeeding duration and the potential lower risk of asthma, for infants with both parents who have no history of allergies or asthma. Article page 182 ▶ Prospective Cohort Study of Breastfeeding and the Risk of Childhood AsthmaThe Journal of PediatricsVol. 195PreviewTo study whether the duration of breastfeeding and time for introduction of complementary foods was associated with the risk of childhood asthma. Full-Text PDF