Lower respiratory tract infections and orofacial clefts: a prospective cohort study from the Japan Environment and Children's Study.

Background Lower respiratory tract infections (LRTIs) are a cause of inpatient and outpatient care among children. Although orofacial clefts seem to be associated with LRTIs, epidemiological studies are scarce on this topic. This study aimed to examine whether infants with orofacial clefts were associated with LRTIs. Methods This prospective cohort study used data from the Japan Environment and Children's Study, whose baseline recruitment was conducted during 2011-2014. This study included 81,535 participants. The number of infants with cleft lip and palate (CLP), cleft lip (CL), and cleft palate only (CP) was 67, 49, and 36, respectively. We defined history of LRTIs until 12 months' age reported by their mothers as the dependent variable. Accumulated breastfeeding duration was used as potential mediators. Results The incidence proportion of LRTIs among the control group was 6.0%. The incidence proportion among infants with CLP, CL, and CP were 11.9%, 14.3%, and 5.6%, respectively. After adjusting for covariates, compared with the control group, infants with CLP and CL were associated with risk of LRTIs (incidence risk ratio [IRR] of CLP = 2.38 [95% confidence interval = 1.30, 4.36] and of CL = 2.73 [1.40, 5.33]) , but not ones with CP (1.08 [0.28, 4.15]). Accumulated breastfeeding duration decreased the IRR of CLP only (IRR of CLP = 2.16 [1.19, 3.93]). Conclusions Infants with orofacial clefts aged 1 year have a potentially high incidence proportion of LRTIs. Accumulated breastfeeding duration might mediate the associations of CLP.