Yoshida K, Wang J, Malspeis S, et al. - Childhood parental smoking exerts a potential direct impact on adult-onset incident seropositive rheumatoid arthritis (RA) even post-controlling for adult personal smoking.

• The Nurses’ Health Study II prospective cohort was examined.

• Of 90,923 women, 532 were found to have incident RA (66% seropositive) during 27.7 years (median) of follow-up.

• A link was found between maternal smoking during pregnancy and RA after confounding adjustment (HR 1.25), but not after accounting for subsequent smoking exposures.

• Post-adjustment for confounders, childhood parental smoking was linked with seropositive RA (HR 1.41).

• No significant link existed between adult passive smoking and RA (20+ years lived smoker: HR 1.30 vs none).