A large Danish study links specific maternal jobs—like ground transportation and military service—to higher odds of autism in children, especially sons.
A study published in Occupational and Environmental Medicine investigated the link between a mother's job and the likelihood of an autism spectrum disorder (ASD) diagnosis in her child, using comprehensive Danish registry data.
Key Details of the Research
- Study Size: The analysis included 1,702 children with ASD and 108,532 control children, all born in Denmark between 1973 and 2012.
- Occupational Categories: Maternal jobs were classified into 42 categories based on Pension Fund records, assessed during three key periods: before conception, during pregnancy, and during infancy. These were further grouped into seven sectors: service, transportation, goods/production, construction, public service, business/finance/hospitality, and STEM.
- Adjusted Analysis: The researchers controlled for factors like the child's sex and birth year, mother's age, number of previous children, neuropsychiatric history, and where the family lived. A secondary analysis also accounted for smoking, marital status, immigration status, and socioeconomic status.
Associations Found
- Specific Occupations with Higher Odds:
- Maternal employment in ground transportation was linked to a 24% increased odds of ASD (adjusted odds ratio 1.24).
- Public administration roles were associated with a 20% increased odds (aOR 1.20).
- Military and defense work showed a 59% increased odds (aOR 1.59).
- Sex-Specific Effects: These associations were particularly significant in male offspring for jobs in ground transportation and defense.
- Judicial Roles: Employment in judicial roles during pregnancy also showed elevated odds, a result that remained significant even after statistical correction.
- Other Jobs: Most other occupational categories did not show consistent, significant associations after the full statistical adjustments.
The authors noted that occupational categories served as broad proxies and did not directly measure toxicant exposures or psychosocial stress.
Important Limitations
- Observational Nature: This is an observational study, meaning it cannot establish causation.
- Statistical Sensitivity: Some associations weakened after adjustments for multiple comparisons or additional sociodemographic factors.
- Exposure Uncertainty: Maternity leave records made it impossible to fully determine whether mothers were physically present at work during the key exposure windows.
- No Direct Measurements: The study did not directly measure specific chemical exposures, stress levels, or other potential workplace hazards.
Conclusions
- The findings suggest that maternal occupational exposures before and during pregnancy may be associated with neurodevelopmental outcomes, with evidence of sex-specific effects.
- The researchers emphasize that further research focusing on specific exposures and underlying mechanisms is needed before any definitive conclusions can be drawn about workplace risks.