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Prenatal ultrasound use and risk of autism spectrum disorder: Findings from the case-control Study to Explore Early
Deborah Christensen1, Karen Pazol1, Katherine J Overwyk1
1National Center on Birth Defects and Developmental Disabilities, Centers for Disease Control and Prevention, Atlanta, Georgia, USA.
Insights
This study found no link between prenatal ultrasounds and autism spectrum disorder (ASD) risk. Research indicates that routine ultrasound use does not increase the likelihood of developing ASD in children.
Area of Science:
- Obstetrics and Gynecology
- Developmental Pediatrics
- Epidemiology
Background:
- Previous studies on prenatal ultrasounds and autism spectrum disorder (ASD) have yielded inconclusive results.
- Despite negative findings, concerns persist due to increasing ASD diagnoses and widespread ultrasound use.
Purpose of the Study:
- To investigate the potential association between prenatal ultrasound exposure and the risk of developing autism spectrum disorder (ASD).
Main Methods:
- A case-control study (Study to Explore Early Development) involving preschool-aged children with ASD and controls.
- Logistic regression models were used to analyze the relationship between ultrasound counts and ASD case status, stratified by maternal medical conditions and pregnancy complications.
- Trimester-specific analyses were conducted using medical record data for detailed exposure timing.
Main Results:
- No association was found between an increased number of prenatal ultrasounds and ASD case status, even when stratified by medical indications for ultrasound.
- Specific analyses examining ultrasound exposure by trimester also revealed no significant link to ASD.
- While ultrasound indications were more common in ASD cases, this did not translate to an increased risk associated with ultrasound frequency.
Conclusions:
- The study provides no evidence to support the hypothesis that prenatal ultrasound use elevates the risk of autism spectrum disorder (ASD).
- Key strengths include rigorous ASD diagnostic assessments, a robust control group, and stratified analyses accounting for confounding factors.
- Findings suggest that current prenatal ultrasound practices are not a contributing factor to the rising incidence of ASD.
Background:
Studies evaluating the association between prenatal ultrasounds and autism spectrum disorder (ASD) have largely produced negative results. Concern remains due to the rising identification of children with ASD and ultrasound use.
Objective:
To evaluate the association between prenatal ultrasound use and ASD.
Methods:
We used data from the Study to Explore Early Development, a multisite case-control study of preschool-aged children with ASD implemented during 2007-2012. We recruited cases from children receiving developmental disability services and randomly selected population controls from birth records. ASD case status was based on in-person standardised assessments. We stratified analyses by pre-existing maternal medical conditions and pregnancy complications associated with increased ultrasound use (ultrasound indications) and used logistic regression to model case status by increasing ultrasound counts. For pregnancies with medical record data on ultrasound timing, we conducted supplementary tests to model associations by trimester of exposure.
Results:
Among 1524 singleton pregnancies, ultrasound indications were more common for ASD cases than controls; respectively, for each group, no indications were reported for 45.1% and 54.2% of pregnancies, while ≥2 indications were reported for 26.1% and 18.4% of pregnancies. The percentage of pregnancies with multiple ultrasounds varied by case status and the presence of ultrasound indications. However, stratified regression models showed no association between increasing ultrasound counts and case status, either for pregnancies without (aOR 1.01, 95% CI 0.92, 1.11) or with ultrasound indications (aOR 1.01, 95% CI 0.95, 1.08). Trimester-specific analyses using medical record data showed no association in any individual trimester.
Conclusions:
We found no evidence that prenatal ultrasound use increases ASD risk. Study strengths included gold-standard assessments for ASD case classification, comparison of cases with controls, and a stratified sample to account for conditions associated both with increased prenatal ultrasound use and ASD.
