Early-life adverse events and risk of inflammatory bowel disease: A Scandinavian birth cohort study.

OBJECTIVES: The experience of childhood stressful or adverse life events is believed to imprint on immunological pathways and, therefore, might have lasting effects on inflammatory bowel disease (IBD) development. This study aimed to examine the association between experiences of early-life adverse events and later IBD risk. METHODS: We followed children in the Norwegian Mother, Father, and Child Cohort Study (MoBa) and All Babies in Southeast Sweden cohort (ABIS) from birth (1997-2009) and linked cohort data to national patient registers to identify IBD diagnoses through the end of 2024 and 2023, respectively. We included 111,293 participants with data on adverse life events reported during pregnancy, by age 1, or by age 3. Adverse life events included adverse maternal or familial events, such as divorce or loss of a family member, based on questionnaire data from the two prospective birth cohorts. Cox regression was used to estimate adjusted hazard ratios (aHRs) for IBD in children exposed versus unexposed to adverse maternal or family events, accounting for parental and child characteristics. Cohort-specific estimates were pooled using a random effects model. RESULTS: We identified 697 IBD events over 2,255,642 person-years of follow-up. Experience of maternal adverse events in pregnancy, reported by 22% of the mothers, was not associated with offspring IBD; pooled aHR 1.00 (95% confidence interval [CI] = 0.57-1.76), compared with no experience. Neither experience of adverse family events by age 1 year (pooled aHR 0.96, 95% CI = 0.80-1.15), nor by age 3 years (pooled aHR 0.99, 95% CI = 0.83-1.17) was associated with later IBD. CONCLUSIONS: This bi-national prospective cohort study found no support for the hypothesis that experiences of early-life adverse events increase the risk of IBD.