The prevalence of rheumatoid arthritis, as well as thyroid disease and epilepsy, was significantly higher in children whose mothers had RA, according to data from a nationwide cohort study in Denmark.

RA runs in families, and many women with RA are concerned about the possible impact of their disease on a developing fetus, wrote Line R. Jølving of Odense (Denmark) University Hospital and the University of Southern Denmark in Odense and her colleagues in Arthritis Care & Research . “However, we do not have sufficient knowledge on the association between maternal RA and long-term chronic childhood outcomes, and still we do not know which specific chronic diseases to be especially aware of in children of women with RA,” they said.

To determine the effect of maternal RA on the prevalence of certain diseases in children, the researchers reviewed data from all live births in Denmark between January 1, 1989, and December 31, 2013, which yielded a study population of 2,106 children born to women with RA and 1,378,539 children born to women without RA.

Overall, the risk of RA was almost three times as high for the children of mothers with RA (hazard ratio, 2.89) as it was for the children of women without RA. In addition, the risk of thyroid disease was more than twice as high (HR, 2.19), and the risk of epilepsy was more than 50% higher (HR, 1.61). Maternal RA during pregnancy had no significant impact on children’s anxiety and personality disorders or on the presence of chronic lung disease.

Mothers with RA were generally older than were those without the condition. The children of mothers with RA were significantly more likely to be born via cesarean section, preterm, and small for gestational age, the researchers said.

The results were limited by the potential inclusion of misclassified diagnoses of child outcomes and by the lack of data on medication use. In addition, the study was not designed to determine the effect of biologic mechanisms or genes, the researchers said. Despite these limitations, “the findings in this study are relevant for pediatricians, rheumatologists, and general practitioners in order to have special awareness of early symptoms of RA, thyroid disease, and epilepsy in offspring of mothers with RA,” they said.

The researchers had no financial conflicts to disclose. The study was funded by several sources, including the Region of Southern Denmark, the University of Southern Denmark in Odense, the Center for Clinical Epidemiology, Odense University Hospital, and the Colitis-Crohn Association in Denmark.

SOURCE:Jølving L et al. Arthritis Care Res. 2017 Dec 11. doi: 10.1002/acr.23461 .