BACKGROUND: Research on the impact of smoking behavior across generations has primarily focused on grandmaternal smoking during pregnancy, while the broader environmental transmission of smoking behaviors remains underexplored. This study aims to evaluate the possibilities of ecological transmission, other than in-utero transmission, regarding the effects of grandparental smoking behavior on their offspring
METHODS: A comprehensive search was conducted across multiple online databases, including PubMed, Embase, Web of Science, and Scopus. There were no restrictions on publication dates, study locations, or language to ensure a broad scope of relevant studies. From the 4133 identified articles, 3916 remained after duplicates were removed. Based on predefined eligibility criteria, 38 articles were selected for full-text assessment. The selection process involved multiple reviewers and the data were independently extracted by multiple reviewers using a standardized protocol. The JBI critical appraisal tool was employed to assess the quality of included studies, with inter-rater reliability tests indicating moderate-to-high agreement.
RESULTS: Seven articles were included in the analysis, measuring grandchildren’s behavior, BMI, fat mass, lean mass, and IQ related to grandparents’ smoking. All studies were conducted in American and European settings. No records were found evaluating the cross-generational effects of grandparents' smoking on grandchildren's development in Asian countries, despite relatively high smoking rates in the region. Indirect relationships occurred in the environmental transmission between grandparents' and grandchildren’s smoking behavior with parental smoking as the mediator. Results suggested indirect environmental transmission between grandparents’ smoking and grandchildren’s outcomes. Significant associations were observed between grandparents’ smoking status and grandchildren’s physical and cognitive outcomes, with notable sex differences.
CONCLUSIONS: This review highlights the potential environmental pathways through which grandparents’ smoking behaviour may influence grandchildren’s behavioural, physical, and cognitive development. While the findings underscore the importance of intergenerational environmental factors, further research is needed to address existing gaps and clarify mechanisms.