Association between maternal exposure to tobacco smoke and fever frequency in children: results from the Japan Environment and Children’s Study

The effects of tobacco smoke exposure on vulnerable populations, such as pregnant women and children, constitute a major public health concern. However, quantitative data linking tobacco smoke exposure to the frequency of fever is lacking. This study investigated the association between maternal tobacco smoke exposure during pregnancy and the frequency of fever in children aged 0 to 3 years. Data from a birth cohort of 68,242 mothers and their children were analyzed. Maternal smoking history and secondhand smoke exposure were assessed. The mother’s urinary cotinine levels were used as an objective biomarker to classify participants as non-smokers, passive smokers, and active smokers. The analysis revealed significant associations between maternal smoking and secondhand smoke exposure during pregnancy and a modestly increased frequency of fever in children. The children of mothers who smoked or were exposed to secondhand smoke during pregnancy had a modestly increased frequency of fever (risk ratio [RR] = 1.071, 95% confidence interval [CI]: 1.020–1.126 and RR = 1.087, 95% CI: 1.039–1.135, respectively). Cotinine analysis confirmed these findings; active smoking was associated with fever frequency (RR = 1.082, 95% CI: 1.044–1.122). Overall, maternal tobacco smoke exposure was associated with a modestly increased frequency of fever in children.