Paternal pre-pubertal passive smoke exposure and impaired lung function trajectories in offspring

<bold>Introduction:</bold> Paternal pre-pubertal passive smoke exposure increases the risk of childhood asthma in offspring, but the impact on lung function was unknown. <bold>Aims:</bold> To assess associations between parental pre-pubertal passive smoke exposure and their offspring’s lifetime obstructive lung function trajectories. <bold>Methods:</bold> Data were analysed from 890 father-offspring and 1,264 mother-offspring pairs from the Tasmanian Longitudinal Health Study. The offspring underwent spirometry at six-time points from 7 to 53 years, with lung function (FEV₁ and FEV₁/FVC) trajectories derived using group-based trajectory modelling. Parents reported their own passive smoke exposure before age 15. Multinomial logistic regressions were used to assess associations between paternal or maternal pre-pubertal passive smoke exposure and offspring’s lung function trajectories. Mediations and interactions were assessed by offspring’s childhood passive smoke exposure and active smoking by midlife. <bold>Results:</bold> Paternal pre-pubertal passive smoke exposure was associated with offspring’s Below Average FEV₁ trajectory (aMOR=1.56 [95%CI: 1.05-2.31]) and Early Low-Rapid Decline FEV₁/FVC trajectory (aMOR=2.30 [1.07-4.94]). The association with the Below Average FEV₁ trajectory was stronger for the offspring with childhood passive smoke exposure (aMOR=2.36 [1.34-4.13]; <italic>p-interaction</italic>=0.053). For observed associations, the indirect effects related to familial smoking history were limited (<15%). No adverse associations were found for maternal passive smoke exposure. <bold>Conclusions:</bold> Paternal pre-pubertal passive smoke exposure may directly impair offspring’s lifetime lung function, highlighting the adverse impact of smoking on multiple generations.