Higher gestational weight gain and maternal hypertensive disorders could be associated with a higher risk of juvenile idiopathic arthritis in offspring.
In a prospective population-based pregnancy cohort study, investigators analyzed participants in the Norwegian Mother, Father and Child Cohort Study and linked cohort data with the Medical Birth Registry of Norway and Norwegian Patient Registry. The primary analytical sample included 78,901 offspring, of whom 265 developed juvenile idiopathic arthritis (JIA). At the end of follow-up in 2023, all participants were aged 14 years and older and 85% were 16 years and older. The registry-based JIA definition previously demonstrated a positive predictive value of 93%.
The investigators evaluated maternal prepregnancy body mass index (BMI), gestational weight gain, birth weight, and hypertensive disorders during pregnancy using logistic regression. Models adjusted for maternal demographic and clinical factors, with covariates varying by exposure.
Each 1–standard deviation (SD) increase in gestational weight gain, corresponding to approximately 6 kg, was associated with 12% higher adjusted odds of JIA and 40% higher odds among those with prepregnancy obesity. Further, higher gestational weight gain was associated with higher odds of JIA among female but not male children. Maternal prepregnancy BMI was not associated with JIA.
Maternal hypertension was associated with 43% higher adjusted odds of JIA, and preeclampsia was associated with 61% higher odds. The composite measure of hypertensive disorders, which included hypertension, preeclampsia, and eclampsia, did not reach statistical significance in the imputed analysis. Birth weight was not associated with JIA in categorical analyses. Mediation analyses found no evidence that hypertension or birth weight mediated the association between gestational weight gain and JIA.
In exploratory analyses, maternal overweight was associated with lower odds of JIA among offspring with low or average genetic susceptibility but not among those with high susceptibility. The investigators cautioned that this finding was based on a small number of JIA cases and should be interpreted with caution.
“Importantly, these exposures may be modifiable, offering potential implications for prevention,” wrote lead study author Vilde Øverlien Dåstøl, of the Department of Rheumatology at Oslo University Hospital in Norway, and colleagues.
Study limitations included residual confounding, possible exposure misclassification, a lack of data on JIA subtypes, a 41% cohort participation rate, and limited generalizability because the participants were predominantly of Northern European descent. The investigators noted that the observational design could identify associations but not establish causality. The findings require further investigation in independent cohorts before informing preventive strategies.
The study was funded by Foundation DAM, the South-Eastern Norway Regional Health Authority, Norwegian Rheumatism Association, the Research Council of Norway, Nordforsk, and South-East Norway Health Authority. Co-author Ole Andreassen reported consulting for Precision Health and receiving speaker honoraria from Bristol Myers Squibb, Eli Lilly, Lundbeck, Janssen, Otsuka, and Sunovion. The study authors reported no other conflicts of interest.
Source: RMD Open
