Background: Early-life environmental exposures may influence immune development and autoimmune disease risk. We examined whether residential greenspace exposure during pregnancy and early childhood was associated with celiac disease (CeD) risk in a national Swedish population-based birth cohort.
Methods: Population-based health registry and environmental data were linked for children born in Swedish hospital between January 1, 2010, and December 31, 2017, using data accessed through the Swedish Initiative for Research on Microdata in the Social and Medical Sciences (SIMSAM). Children with missing birth dates, emigration from Sweden, or missing greenspace estimates during pregnancy or childhood were excluded. Migration data were obtained from Statistics Sweden, pregnancy/ neonatal data from the Medical Birth Register, and CeD diagnoses from the CeD Register. Residential greenness exposure was estimated using the Normalized Difference Vegetation Index(NDVI) within 250 m buffers around residential addresses during pregnancy, at birth, and in early childhood. Associations with CeD were assessed using hazard models.
Results: Among 923,158 children, 1018 were diagnosed with CeD. Higher greenspace exposure generally yielded hazard ratios below 1.0, suggesting a possible protective association, but most estimates were not statistically significant. In the main model, birth NDVI was not associated with CeD risk (HR 0.79, 95% CI 0.48-1.32; p=0.372). Seasonal and interaction analyses were nonsignificant. A sensitivity analysis showed a borderline significant inverse association for highest childhood NDVI adjusted for birth year (HR 0.56, 95% CI 0.31-1.00; p=0.0494).
Conclusions: Early-life greenspace exposure was not consistently associated with CeD risk, although findings were directionally suggestive of a protective effect. Limited follow-up may have missed later-onset cases. Longer follow-up is needed to clarify whether the borderline inverse association for childhood NDVI persists as additional CeD cases are identified. While differing from prior findings in Skåne(1), this national study contributes to the broader literature on early-life environmental exposures and CeD risk.