Parental pre-pubertal passive smoke exposure and Early-Onset Adult-Remitting asthma trajectory in offspring

<bold>Introduction:</bold> Paternal pre-pubertal passive smoke exposure is associated with childhood asthma in offspring, but the long-term impact was unknown. <bold>Aims:</bold> To investigate associations between parental pre-pubertal passive smoke exposure and offspring’s asthma trajectories to midlife. <bold>Methods:</bold> Data were analysed from 1,078 father-offspring and 1,537 mother-offspring pairs from the Tasmanian Longitudinal Health Study. Parents reported their passive smoke exposure before age 15. Offspring asthma was assessed at 7, 13, 18, 30, 43, 50 and 53 years. Asthma trajectories were developed by group-based trajectory modelling. Multinomial logistic regressions were used to assess associations between paternal or maternal pre-pubertal passive smoke exposure and asthma trajectories in their offspring. Mediations and interactions were assessed for 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 Early-Onset Adult-Remitting asthma trajectory (aMOR=2.49 [95%CI: 1.07-5.76]), but not Persistent asthma into mid-adult life. Maternal pre-pubertal passive smoke exposure showed a weaker association with offspring’s Early-Onset Adult-Remitting asthma trajectory (aMOR=1.97 [0.90-4.28]), but the association was augmented in offspring additionally exposed to childhood passive smoke (aMOR=4.35 [1.02-18.58]; <italic>p-interaction</italic>=0.044). The observed associations were minimally (<11%) mediated through factors related to familial smoking. <bold>Conclusions:</bold> Parental pre-pubertal passive smoke exposure increases the risk of offspring asthma. Offspring’s childhood passive smoke strengthens this effect in mother-offspring pairs.