Sun K, et al. - Researchers analyzed data from studies assessing and comparing the impact of environmental tobacco smoke (ETS) by different family members and prenatal smoke exposure on the risk of habitual snoring (HS) in children. The meta-analysis included a total of 24 studies with 87,829 participants. These studies, published in English, were identified by a search of PubMed, Embase and Web of Science up to December 2017. Using random effect model and fixed effect model, data were pooled. The evaluation of the dose-response relationship was carried out using restricted cubic splines. Findings from observational studies revealed an association between exposure to ETS, in particularly prenatal tobacco smoke exposure and maternal smoking, and an increased risk of HS.