This case-control study has found an association between maternal metabolic conditions (diabetes, hypertension and obesity) during pregnancy and the chances of children having autism and developmental delays. These conditions were also associated with lower scores on several markers of development, particularly expressive language.
Due to the study design, this study can only show that metabolic conditions are associated with these outcomes. Case-control studies are useful for investigating rare conditions, such as autism spectrum disorder, as case-control studies start with people known to have the outcome, and therefore allow researchers to have sufficient number of patients to study in a meaningful way. However, case-control studies also have limitations. For example:
- The controls were selected carefully, to minimise the risk of bias, but it is still possible mothers could have been generally healthier for a number of reasons, including socioeconomic status. This could partially explain the explain the associations seen in the study.
- Also, the study relied partly on the mother’s report of her health during pregnancy. This leaves the possibility that there may have been inaccuracy in recording this information, although the researchers did compare a proportion of the results to medical records, and found good agreement.
The exact causes of autism are still not known, but the latest research is looking at the potential genetic and environmental causes of the condition. While this research has provided results suggesting a potential link to maternal metabolic conditions (defined as obesity, diabetes and blood pressure), it should be remembered that the study only found associations rather than a cause-and-effect relationship.
The authors have raised serious public health concerns about rising levels of obesity and the possibility of a link with autism. However, further studies, perhaps of a prospective nature, are needed to continue assessing this potential link. While waiting for definitive proof, staying a healthy weight during pregnancy remains a good idea.
Links to the headlines
Obesity and diabetes link to child disorders. BBC News, April 10 2012
Obese mothers more likely to have children with autism. The Daily Telegraph, April 10 2012