Total Fish Intake in Pregnancy Could Alter Risk of Juvenile Arthritis in Offspring


EULAR 2024 data link maternal intake of over 252 grams of fish per week with higher risk of juvenile idiopathic arthritis in offspring, but causation is unclear.

Vilde Øverlien Dåstøl, MD | Credit: Oslo University Hospital

Vilde Øverlien Dåstøl, MD
Credit: Oslo University Hospital

Data from a study presented at the European Alliance of Associations for Rheumatology (EULAR) 2024 Congress suggests increased intake of fish, whether oily or lean, was associated with an elevated risk of offspring with juvenile idiopathic arthritis (JIA).

An analysis of a prospective birth cohort following more than 15,000 children, results of the study demonstrate maternal intake of more 252 grams or more of fish oil per week was associated with greater odds of offspring developing JIA, but investigators underline their study was unable to determine causation.1

“We found increased odds of JIA when the maternal intake exceeded 252 grams of lean or semi-oily fish per week compared with low intake”, said Vilde Øverlien Dåstøl, MD, of the Oslo Univeristy Hospital. “But 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 emphasize that while our data indicates an association, causation cannot be definitively inferred.”

A staple in the diets of millions across the globe, the effect of fish consumption has come into question as research has further elucidated the association with elevated exposure to heavy metals, particularly mercury. The current study was launched by Dåstøl and colleagues from Norway to build on previous research suggesting consuming fish 1 or more times per week in pregnancy and during the first year of life was associated with a 5-fold increase in risk of JIA, but this link was attributed to elevated exposure to heavy metals.1,2

With this in mind, investigators designed their study as an analysis of data from the Norwegian Mother, Father, and Child Cohort Study (MoBa). A prospective birth cohort study, the endeavor enrolled pregnant women between 1999 through 2008 and investigators determined diagnoses of JIA using linkage to the Norwegian Patient Registry to identify children with presence of at least 2 ICD-10 codes.1

As part of the MoBa study, maternal fish consumption was assessed through a validated food frequency questionnaire, with high consumption defined as exceeding the 90th percentile, which investigators determined was 252 grams for week for lean and semi-oily fish, 157.5 grams per week for oily fish, and 427 grams per week for total fish intake. For the purpose of analysis, those meeting these criteria were compared against those with low consumption, which was defined as anything in the 90th percentile or below.1

Investigators used odds ratios (OR) to estimate effect of fish intake on likelihood of developing JIA. Investigators pointed out age, education, pre-pregnancy BMI, parity, daily caloric intake, inflammatory rheumatic disorders, and parental smoking in pregnancy were used as covariates in adjusted analyses.1

Overall, 73,819 mother-child pairs were identified for inclusion. Among this cohort, 218 cases of JIA were identified among offspring. The cohort of pregnant women had a mean age of 30.3 years, a mean BMI of 24.1 kg/m2, median total fish intake of 218 grams per week, and 2.9% had inflammatory rheumatic disease.1

Results of the analysis found high intake of lean and semi-oily fish was associated with an increased likelihood of JIA in offspring (aOR, 1.53; 95% CI, 1.04 to 2.24) relative to those with low consumption. Further analysis demonstrated no clear associations between JIA and high consumption of oily (aOR, 0.93; 95% CI, 0.58 to 1.48) and total fish (aOR, 1.1; 95% CI, 0.71 to 1.71) relative to low consumption. Investigators highlighted no association was observed between JIA and mercury intake (aOR, 0.94; 95% CI, 0.59 to 1.50).1

“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,” Dåstøl added.2


  1. DåstølVØ, Caspersen IH, BrantsæterAL, Sanner H. THE PREVALENCE AND IMPACT OF COMORBID FIBROMYALGIA IN RHEUMATOID ARTHRITIS. Abstract presented at Annual European Congress of Rheumatology (EULAR) 2024. Vienna, Austria. June 12-15, 2024.
  2. EULAR. Is fish intake linked to Jia? EurekAlert! June 14, 2024. Accessed June 20, 2024.

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