Alterman N, et al. - As birth by cesarean section has been linked with raised risk of lower respiratory tract infections in the child in several studies and upper respiratory tract infections are commonly observed during childhood, researchers here examined if cesarean is also a risk factor for this site of infection. Two UK cohorts were assessed for retrieving data: the Millennium Cohort Study (MCS) and linked administrative datasets of the population of Wales through the Secure Anonymised Information Linkage (SAIL) databank. They included 15,580 infants born 2000–2002 (MCS) and 392,145 infants born 2002–2016 (SAIL) focusing on term-born singleton infants. Analyses revealed a moderately elevated risk of severe LRTIs during infancy in infants born by planned cesarean compared with those born vaginally. Infants born by any type of cesarean may exhibit a small elevated risk of severe URTIs. Stronger estimated effect sizes are observed when inclusion was performed of the indirect effect arising from planning the cesarean birth for an earlier gestation than would have occurred spontaneously.