Exposure to maternal smoking and incident SLE in a prospective cohort study

Current cigarette smoking is a risk factor for SLE, and recent work has demonstrated that early-life smoke exposure was related to the risk of related rheumatic conditions in female children. Therefore, we sought to investigate whether early-life cigarette smoke exposure might be associated with incidence of SLE in adult women. We studied 93,054 Nurses' Health Study (NHS) and 95,554 NHSII participants free of SLE at baseline who provided information on perinatal exposures. By medical record review, 236 incident SLE cases were confirmed (142 NHS and 94 NHSII) among these women using American College of Rheumatology criteria. We used stratified Cox models to estimate the association of smoke exposure with SLE adjusting for race, birth weight, preterm birth and parents' occupation. Combined estimates were computed using random effects meta-analytic techniques. Maternal cigarette smoking did not increase the risk of SLE (relative risk (RR) = 0.9, 95%CI: 0.6 to 1.4) nor did paternal smoking during the participant's childhood (RR = 1.0, 95% CI: 0.8 to 1.3) in combined analyses. Early-life exposure to cigarette smoke due to mothers' or fathers' smoking was not associated with increased risk of adult-onset SLE in women.