Maternal Smoking during Pregnancy: A Review of the Effects of Maternal Tobacco Use on Fetal Brain Development

Background: Maternal smoking during pregnancy (MSDP) is greatly associated with serious health outcome for offspring. Citing from past studies to present, experiments have been conducted to examine the association between maternal smoking and fetal brain development. A majority of these studies have focused more on indirect association and little or nothing on direct association. This review paper seeks to examine studies conducted on the direct relationship between maternal smoking and fetal brain development. Method: A systematic search of Psyc-INFO, Medline, Scopus, Web of Science and Embase was conducted (1977-2017) and 116 studies were identified with nine studies meeting inclusion criteria gathering data from over 4,000,000 participants. All studies measured outcomes using either internalizing (anxiety, depression, cognition) or externalizing (over action, aggressiveness, head circumference) behaviors or both. Results: All the studies showed an indirect association between maternal smoking and fetal brain development and none could show how cigarette smoke affects fetal brain development directly. Five studies used internalizing behavior to show this indirect association and the remaining four used the externalizing behavioral outcome. Some studies predicted the smoke not to be the main cause for the abnormalities during brain development but the confounding factors are responsible for the unhealthy outcomes on brain development. Conclusion: However, heterogeneity in the timing of brain development, assessment measures used for mother smoking habit and inconsistencies in adjustment for confounders, limits the synthesis and interpretation of findings. Moreover, if direct affect is to be attained, different measures and designs of prospect studies be required to investigate this complex association between maternal smoking during pregnancy and fetal brain development.