NEW data has linked the consumption of fish during pregnancy and the first year of life with juvenile idiopathic arthritis (JIA). In 2019, a Swedish birth cohort study of 15,000 children suggested that consuming fish at least once a week during pregnancy and the first year of life was associated with up to a five-fold increased risk of JIA, potentially due to elevated heavy metal exposure. This new research, presented at the European Alliance of Associations for Rheumatology (EULAR) 2024 Congress, investigated the association between the risk of JIA and maternal fish consumption of dietary mercury exposure during pregnancy.
The large, population-based prospective cohort study utilised data from the Norwegian Mother, Father, and Child Cohort Study, which recruited pregnant women from 1999–2008. JIA cases were identified through linkage to the national patient registry, and maternal fish consumption during the first half of pregnancy was assessed via a food frequency questionnaire. High fish consumption was defined as exceeding the 90th percentile: 252 g/week for lean and semi-oily fish, 157.5 g/week for oily fish, and 427 g/week for total fish intake. Dietary mercury exposure was estimated from fish consumption data, with high intake classified as more than 20 μg/week. The study adjusted for various maternal factors including age, education, pre-pregnancy body mass index, parity, daily caloric intake, inflammatory rheumatic disorders, and parental smoking during pregnancy.
The analysis included 73,819 mother–child pairs, identifying 218 cases of JIA. The median total fish intake was 218 g/week. Results indicated a positive association between JIA and high consumption of lean and semi-oily fish compared to low consumption. However, no clear associations were found between JIA and high consumption of oily fish or total fish intake. Additionally, no significant association was observed between JIA and high mercury intake.
“The magnitude of our effect estimates was substantially smaller than the Swedish study, and we found no association between total fish consumption or estimated dietary mercury exposure and JIA. It is crucial to emphasise that while our data indicates an association, causation cannot be definitively inferred,” explained lead researcher Vilde Øverlien Dåstøl. “Therefore, we cannot caution pregnant women against consuming fish solely based on this study in regards to JIA risk, especially considering other research highlighting the positive impacts of a marine diet.”
Reference
Dåstøl VØ, et al. Fish consumption and dietary mercury exposure during pregnancy and JIA risk: a population-based nationwide cohort study. European Alliance of Associations for Rheumatology (EULAR) 2024 Congress, 12-15 June, 2024.
