Parental preconception BMI trajectories from childhood to adolescence and asthma in the future offspring

Abstract

Recent evidence suggests that parental exposures before conception can increase the risk of asthma in offspring. We investigated the association between parents' preconception body mass index (BMI) trajectories from childhood to adolescence and subsequent risk of asthma in their offspring. Using group-based trajectory modeling from the Tasmanian Longitudinal Health Study, we identified BMI trajectories for index participants (parents) when aged 4 years to 15 years. Multinomial regression models adjusted for potential confounders were utilized to estimate the association between these early-life parents' BMI trajectories and asthma phenotypes in their subsequent offspring. The main analysis included 1822 parents and 4208 offspring. Four BMI trajectories from age 4 years to 15 years were identified as the best-fitting model: low (8.8%), normal (44.1%), above normal (40.2%), and high (7.0%). Associations were observed between father's high BMI trajectory and risk of asthma in offspring before the age of 10 years (relative risk ratio [RRR]=1.70 [95% CI= 0.98-2.93]) and also asthma ever (RRR= 1.72 [95% CI= 1.00-2.97]), especially allergic asthma ever (RRR= 2.05 [95% CI= 1.12-3.72]). These associations were not mediated by offspring birth weight. No associations were observed for maternal BMI trajectories and offspring asthma phenotypes. This cohort study over 6 decades of life and across 2 generations suggests that the high BMI trajectory in fathers, well before conception, increased the risk of asthma in their offspring.