Regional differences in autism and intellectual disability risk associated with cesarean section delivery.
Deborah A Bilder, Scott Sullivan, Michelle M Hughes and 4 others
PMID 39420702WHAT IT FOUND
Cesarean delivery was associated with modestly higher odds of autism and intellectual disability, but this link varied by region and weakened after adjustment.
The association likely reflects shared maternal health risks rather than the surgery itself causing disability.
Key findings
01Primary and repeat C-sections were associated with a modest increase in odds for autism with or without intellectual disability and intellectual disability alone, while vaginal birth after C-section showed no such association.
02The association between repeat C-section and developmental disability varied by region, with significant links in the Southeast and Mid-Atlantic but attenuated results in the West.
03Regional differences in maternal health factors like obesity and diabetes likely contributed to the varying associations, suggesting residual confounding rather than a direct causal effect of the C-section.
STILL TO COME
How it was doneWhat they found
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What it does not show
The study lacked data on maternal metabolic conditions (e.g., obesity, diabetes), which are risk factors for both C-section and developmental disabilities, limiting the ability to rule out confounding. Information on whether a trial of labor preceded the C-section was unavailable. Reliance on birth records may introduce inaccuracies regarding complex obstetrical factors. The records review method may bias case ascertainment toward children with better access to developmental assessments and services. The sample is not nationally representative, as it only includes regions with ADDM sites that conducted concurrent ASD and ID surveillance.
Declared interests
Deborah Bilder is a consultant for Encoded Therapeutics, BioMarin Pharmaceuticals, Synlogic Therapeutics, and Taysha Gene Therapies, and has attended an advisory board meeting for Sanofi. The remaining authors report no conflicts of interest.
The easy way to misread this
Do not interpret the association between C-section and developmental disability as evidence that the surgery itself causes autism or intellectual disability. The study indicates that shared maternal health factors and regional variations likely explain the link, and the association weakened after adjusting for these confounders.