Babies of moms with RA have increased risk of some chronic diseases

Children born to women with rheumatoid arthritis (RA) may be more likely to develop certain chronic diseases during childhood and adolescence, according to a study published in Arthritis Care & Research.

In utero exposure to maternal RA was associated with an increased risk of thyroid disease and epilepsy, as well as childhood and adolescent RA, compared to children born to mothers without RA, reported the authors, led by Line R. Jølving, graduate student, Odense University Hospital, University of Southern Denmark, Odense.

One of the most common chronic diseases in pregnancy is RA, an autoimmune disease that is more likely to develop in women and which may have a genetic component. Women with RA often have concerns about the impact of their disease on the fetus. Some studies have reported that early adverse fetal life exposures can result in growth restriction and low birth weight, which has been linked to chronic diseases later in life.

These researchers set out to assess fetal exposure to maternal RA and the risk of developing 15 selected chronic diseases. They used the Danish health registry to identify children born from 1989 to 2013, which included 2,106 born to women with a diagnosis of RA within 10 years before childbirth and 1,378,539 born to women without RA. Babies were followed until an important health outcome, death, or the end of the follow-up period. Median follow-up time was 13.7 years, with a maximum of 25.9 years.

Interestingly, the proportion of women with RA giving birth increased significantly, from 7.4% in the first 5-year period (1989-1993) to 35% in the last 5 years (2009-2013). Furthermore, at time of birth, more women in the exposed cohort were aged 30-39 years (58.6%) than women in the unexposed cohort (46.9%). One possible reason for this may be that women with RA wait for low disease activity to become pregnant, and it may take longer to achieve pregnancy due to reduced fertility.

Jølving and colleagues also found that babies born to moms with RA were more likely to be born by cesarean section compared to unexposed babies (28.2% vs 15.0%, respectively), more frequently born preterm (10.1% vs 6.2%), and more likely to be small for gestational age (5.1% vs 3.8%).

In children born to women with RA, these researchers found significant outcome associations with thyroid diseases, epilepsy, and RA (hazard ratios [HRs] 2.19, 1.61, and 2.89, respectively). In the sensitivity analysis, which included those diagnosed with RA on at least two occasions before childbirth, the exposed cohort was reduced to 1,067 children, and results were similar to the main analysis for both epilepsy and RA, but did not hold for thyroid diseases.

Other diseases evaluated in the study included non-insulin dependent diabetes mellitus, parathyroid disease, polycystic ovary syndrome, systemic lupus erythematosus, inflammatory bowel disease, multiple sclerosis, coagulation disorders, chronic lung disease including asthma, affective mood disorder, schizophrenia and other paranoid psychoses, and anxiety and personality disorders.

The investigators did not include information regarding the medication used by mothers or socioeconomic factors in their analyses. Furthermore, it is possible that some child outcomes are misclassified.

“The results from our study suggest that children of mothers with RA have excess morbidities during childhood and adolescence when it comes to important chronic diseases,” concluded the authors. They suggest that their results need to be confirmed with data from other countries and that studies to explore underlying biological mechanisms are needed.