Breastfeeding and respiratory tract infections during the first 2 years of life

Breastfeeding protects against respiratory tract infections (RTIs) in infants [1–3], but whether its effects persist beyond that age is not well understood. Some studies have reported that protection diminishes soon after weaning [2], while others have found that it extends until the age of 2 years [4] or more [5, 6]. It is noteworthy that many previous studies grouped RTIs broadly into upper or lower tract infections, rather than studying specific diseases [3, 7], and few adjusted adequately for confounding factors [5] or investigated a possible effect modification by sex, which had been suggested by several studies showing a stronger protection in girls [8, 9]. Breastfeeding and respiratory tract infections <http://ow.ly/Isd9309JS69> The authors thank the parents of the Leicester Respiratory Cohorts children for completing the questionnaires, Cristian Dogaru (School of Applied Social Science, University Campus Suffolk, Ipswich, UK) for contributing to dataset management, and Kali Tal (Institute of Social and Preventive Medicine, Bern, Switzerland) for her editorial assistance. C.E. Kuehni and J. Wang developed the concept and designed the study. J. Wang performed the statistical analyses under the guidance of A. Ramette. C.E. Kuehni, J. Wang, M. Goutaki and A. Ramette drafted the manuscript, and all authors contributed to iterations and approved the final version. All authors take final responsibility for the content of this article.