Prenatal exposure to ambient temperature variation increases the risk of common cold in children.

BACKGROUND: Common cold is a frequent upper respiratory tract infection, but the role of ambient temperature in the infection is unclear. OBJECTIVE: We investigated the role of prenatal exposure to diurnal temperature variation (DTV), the difference between the daily maximal and minimal temperatures, in the risk of common cold in children. METHODS: We conducted a cohort study of 2598 preschool children in Changsha, China. Occurrence of common cold during the past year was surveyed using questionnaire. We then estimated each child's prenatal exposure to DTV during pregnancy. Multivariate logistic regression model was used to examine the association between occurrence of common cold and prenatal exposure to DTV in terms of odds ratios (OR) and 95% confidence interval (CI). RESULTS: About 45% children have common cold (≥3 times) during the past year. We found that common cold in children was associated with maternal DTV exposure during pregnancy, particularly during the first trimester with adjusted OR (95% CI) = 1.27 (1.10-1.46). Male and atopic children were more susceptible to the effect of DTV during pregnancy. The risk of common cold due to DTV is higher in children living in the suburban areas and the bigger houses and in those exposed to environmental tobacco smoke, mold/dampness, new furniture and redecoration. We observed that the risk of common cold in children has been increased in recent years due to increasing DTV. CONCLUSIONS: Common cold in children was associated with maternal exposure to temperature variation during pregnancy, suggesting that the risk of common cold may originate in pregnancy.