Parental smoking and blood pressure in children and adolescents: a national cross-sectional study in China.

Background: Current evidence on the health effects of passive smoking on childhood blood pressure is limited and inconsistent. We investigated the associations between exposure to parental smoking and blood pressure in children and adolescents.
Methods: A cross-sectional analysis was performed in a national sample of 42,745 children and adolescents (50.2% boys) aged 7-18 years from seven provinces in China. Systolic blood pressure (SBP) and diastolic blood pressure (DBP) were measured. Information on parental smoking was collected through questionnaire. Multivariable linear regression and logistic regression was used to investigate the associations of parental smoking with blood pressure and prevalent hypertension, respectively.
Results: The reported parental smoking rates were 49.7 and 50.2% in boys and girls, respectively. After adjustment for a range of potential confounders, exposure to parental smoking was associated with 0.44 [95% confidence interval (CI): 0.16, 0.72] mmHg and 0.26 (95% CI: 0.04, 0.47) mmHg higher SBP and DBP in girls. Girls exposed to parental smoking were also more likely to have hypertension compared with those without exposure (odds ratio = 1.11, 95% CI: 1.02, 1.20). No significant associations were found in boys.
Conclusions: Exposure to parental smoking was associated with increased blood pressure and higher prevalence of hypertension in girls, but not in boys. Urgent strategies are needed for the promotion of smoking-free environment, especially for children and adolescents.