A nationwide cohort study based on the Danish health registries shows that children born to mothers with rheumatoid arthritis (RA) are more susceptible to developing RA and other chronic diseases compared with children born to women without RA. Children exposed to RA in utero were nearly three times more likely to develop RA (HR 2.89, 95% CI 2.06–4.05). The study additionally found that these children were also at an increased risk of developing thyroid diseases (HR 2.19, 95% CI 1.14–4.21) and epilepsy (HR 1.61, 95% CI 1.16–2.25).