OBJECTIVE: Maternal rheumatoid arthritis (RA) has been associated with an increased risk of autism spectrum disorder (ASD) in the offspring. We assessed the potential influence of both maternal and paternal RA on the risk of ASD in offspring to disentangle the influence of genetic inheritance from other conditions potentially leading to fetal programming.

METHOD: The nationwide cohort study included all children born alive from 1977 to 2008 in Denmark (N = 1,917,723). Cox regression models were used to calculate hazard rate ratios (HR) of ASD in offspring exposed to maternal or paternal RA, compared to unexposed children.

RESULTS: Maternal RA was associated with an approximately 30% increased risk of ASD in the offspring (HR = 1.31 and 95% CI = 1.06-1.63). Also, paternal RA seemed to increase the risk of ASD by approximately 30% (HR = 1.33, 95% CI = 0.97-1.82).

CONCLUSION: Our findings suggest maternal as well as paternal RA to be associated with an increased risk of ASD in the offspring, indicating that genetic factors associated with RA may also play a role in the etiology of ASD in children of parents with RA.