Netherlands: Interventions targeting maternal smoking cessation before pregnancy or in early pregnancy are necessary because continued maternal tobacco use during pregnancy is associated with suboptimal brain development among offspring in preadolescence, reports a study article published in the JAMA Network Open.
Survey reports, that globally more than 50% of the women who smoked daily, continued to do so even during pregnancy. Despite the well-documented risks of tobacco use, the prevalence of cigarette smoking during pregnancy is still high; it varies considerably across different countries and socioeconomic groups. Maternal tobacco use during pregnancy affects the health of not only the mother but also her offspring. Evidence suggests that maternal tobacco use during pregnancy has been associated with various health consequences including suboptimal neurodevelopment in offspring. However, the effect of prenatal exposure to maternal smoking on child brain development has yet to be elucidated.

Runyu Zou, University Medical Center Rotterdam, the Netherlands, and the research team conducted a cohort study to investigate the association between maternal smoking during pregnancy and offspring brain development in preadolescence as well as the mediating pathways.
Researchers included 2704 children[mean (SD) age of 10.1 (0.6) years] with information on maternal tobacco use during pregnancy and usable brain magnetic resonance imaging (MRI) data at 9 to 11 years of age for the study. The present study was embedded in the Generation R Study. A subsample of 784 children with data on DNA methylation at birth was examined in the mediation analysis. Information on maternal smoking during pregnancy was collected via a questionnaire in each trimester. In contrast, paternal smoking was assessed at recruitment.
Researchers assessed brain morphology, including brain volumes and surface-based cortical measures (thickness, surface area, and gyrification), with MRI. For mediation analysis, DNA methylation at birth was quantified by a weighted methylation risk score.
Key findings of the study,
• Exposure to continued maternal smoking during pregnancy was associated with smaller total brain volume (volumetric difference [b] = −14.5 cm3), cerebral grey matter volume (b = −7.8 cm3), cerebral white matter volume (b = −5.9 cm3), and surface area and less gyrification as compared to unexposed children.

• The associations were not explained by paternal smoking nor mediated by smoking-associated DNA methylation patterns at birth.
• Children exposed to maternal smoking only in the first trimester showed no differences in brain morphology compared with nonexposed children.
Based on the study results, researchers conclude that continued prenatal exposure to maternal smoking is associated with lower brain volumes and suboptimal cortical traits of offspring in preadolescence, which seemed to be independent of shared family factors. Tobacco cessation before pregnancy, or as soon as pregnancy is known, should be advised to women for healthy growth and optimal brain development of their offspring.
Reference:
Zou R, Boer OD, Felix JF, et al. Association of Maternal Tobacco Use During Pregnancy With Preadolescent Brain Morphology Among Offspring. JAMA Netw Open. 2022;5(8):e2224701. doi:10.1001/jamanetworkopen.2022.24701