Does exposure to black carbon during pregnancy increase the risk of autism spectrum disorder? A cohort study from Southern Sweden.

This large Swedish study looked at whether air pollution during pregnancy increases autism risk. Researchers followed over 40,000 children and measured exposure to black carbon (a type of air pollution) throughout pregnancy. They found a small increase in autism risk with higher pollution exposure, but this link became unclear when other factors were considered. The study suggests air pollution might play a role in autism development, but more research is needed to be certain.

This Swedish cohort study examined 40,156 individuals to investigate whether prenatal exposure to black carbon (BC) increases autism spectrum disorder (ASD) risk. Researchers used high-quality register data from the Malmö region, tracking air pollution exposure throughout pregnancy. Results showed a modest positive association between BC exposure and ASD, with an adjusted odds ratio of 1.17 (95% CI: 0.97-1.41) per interquartile range increase in BC exposure. However, this association became non-significant after adjusting for covariates.

Non-BC fine particulate matter showed a stronger association (OR: 1.22, 95% CI: 1.00-1.49). The study utilized precise individual-level data with reliable diagnoses made by a single team, providing valuable evidence for future meta-analyses on environmental risk factors for ASD.

Results suggest prenatal air pollution exposure may contribute to ASD risk, but evidence is not conclusive. Healthcare providers should be aware of potential environmental factors while recognizing the complex, multifactorial nature of ASD development. Findings support broader public health initiatives to reduce air pollution exposure during pregnancy.

Single geographic region (Malmö, Sweden) limits generalizability. Observational design cannot establish causation. Association became non-significant after covariate adjustment, suggesting potential confounding. Limited to low exposure settings which may not reflect higher pollution environments.

Black carbon (BC), a major component of fine particulate matter (PM), has been implicated in adverse neurodevelopmental outcomes, including autism spectrum disorders (ASD). While PMhas been associated with increased ASD risk, the specific role of BC remains uncertain. This study aimed to assess prenatal exposure to BC and risk for ASD development in a low exposure setting, using a large, high-quality register database, with disease diagnosis made by a single team. We used the Maternal Air Pollution in Southern Sweden cohort, encompassing nearly all births in the Malmö region, linked with ASD diagnoses.

Exposure estimates included locally emitted PMand BC, based on residential address during the entire pregnancy and for each trimester separately. Odds ratios were estimated with logistic regression models, adjusted for potential confounders. The final analytical cohort included 40,156 individuals. Associations between prenatal exposure to BC and ASD were observed in multiple models and across different trimesters, with an adjusted odds ratio (OR) of 1.17 (95 % CI: 0.97-1.41) per intra-quartile range (IQR) increase in BC exposure over the full pregnancy.

For non-BC PM, the OR was 1.22 (95 % CI: 1.00-1.49) per IQR increase. This study utilised a large, high-quality register of births, matched to residential addresses and demographics factors, with a highly reliable disease outcome, against high-quality air pollution models. Positive trends were seen between BC exposure and ASD outcome, which were attenuated slightly, and becoming non-significant, when controlling for covariates. We observed stronger associations for PMthan BC.

This study is novel in the precision of individual data, exposure and diagnosis, and is useful for future meta-analyses.