Prenatal, infantile, and childhood tobacco exposure and risk of pediatric psoriasis in the Danish National Birth Cohort offspring

Background: Tobacco smoking is implicated in psoriasis among adults. Objective: To determine whether prenatal, infantile, and childhood tobacco exposure increase risk of pediatric psoriasis. Methods: Data from Danish National Birth Cohort participants were collected at approximately gestational week 12 and when the children were approximately 6 months and 11 years of age. In total, 25 812 offspring with complete data from the Danish National Birth Cohort were included. We estimated the odds of pediatric psoriasis with tobacco exposure prenatally, from birth to age 6 months (early infancy), and at age 11 years (childhood). Results: We observed an increased risk of pediatric psoriasis among offspring with prenatal tobacco exposure (adjusted odds ratio [OR], 1.39; 95% confidence interval [CI], 1.06-1.82). An exposure-response relationship was observed for increasing quantities of cigarettes smoked daily (>= 16 cigarettes: adjusted OR, 2.92; 95% CI, 1.20-7.10; P for trend = .038). The associations with infantile (adjusted OR, 1.17; 95% CI, 0.76-1.79) and childhood (adjusted OR, 1.10; 95% CI, 0.77-1.58) tobacco exposure were attenuated after controlling for prenatal exposure. Limitations: Outcome status was maternally reported. Conclusions: Prenatal tobacco exposure may increase the risk of pediatric psoriasis in a monotonic fashion, indicating that smoking may play a causal role in psoriasis pathogenesis.