Is maternal smoking during pregnancy associated with childhood brain tumors? A systematic literature review

With a global prevalence of 1.7%, smoking during pregnancy commonly still occurs in many countries. Tobacco smoke contains several harmful and carcinogenic compounds which can cross the placental barrier and cause adverse effects on maternal and fetal health. Developing brains are particularly sensitive to the harmful effects of chemical exposures. The aim of this systematic literature review was to investigate the association between maternal smoking during pregnancy and childhood brain tumors in children aged 0-15 years. A systematic search was conducted using PubMed, Web of Science, CINAHL, and Scopus databases. Of the initial 192 articles, 18 were included in the final analysis, which comprised of three cohort studies and 15 case-control studies. Studies were evaluated for study quality using The National Health, Lung and Blood Institute Study Quality Assessment Tools website and the quality of the studies was mostly good. This systematic literature review found no consistent evidence of an association between maternal tobacco smoking during pregnancy and childhood brain tumors. Of the 18 studies, four reported an association between maternal smoking during pregnancy and childhood brain tumors (CBT), ependymoma, or astrocytoma. If there was an association between CBT and maternal tobacco smoking, it was seen more commonly in young children, ranging from 0 to 4 years. Further studies are needed to establish a more comprehensive understanding.