Here is just a partial list of correlates, risk factors, and possible causes that have been the subject of serious studies:
• Air pollution and proximity to freeways;
• Maternal thyroid issues;
• Autoimmune disorders;
• Induced labor;
• Preterm birth;
• Birth by cesarean section;
• Maternal and paternal obesity;
• Maternal and paternal age;
• Maternal post-traumatic stress disorder;
• Smoking during pregnancy;
• Antidepressant use during pregnancy.
A mountain of research has been conducted and published on a possible link between vaccines and autism, with hundreds of advocacy and scientific organizations refuting it. They also point out the public health risk of avoiding vaccinations. Yet the fear this unsubstantiated link has generated has led to the re-emergence of vaccine-preventable diseases such as measles and pertussis. Another consequence of the ongoing media attention paid to the issue is a misunderstanding of the real environmental risk factors associated with autism.
Here are a few examples of environmental factors that that have been linked to autism:
- Exposure to the anti-epileptic drug valproic acid during pregnancy
- Older age of the mother or father
- High levels of air pollution during pregnancy. This association has been subjected to a systematic review and withstood scientific rigor. Genes control this association.
- Extreme illness or infection during pregnancy, including severe reactions to bacterial and viral infections (some of which can be prevented through vaccination)
- Obesity during pregnancy, premature birth, and complications during birth, likely as the result of interactions with genes
Exposure to these factors elevates a child’s risk of developing autism anywhere between two and four times. An exhaustive review of these factors was just published in the Annual Review of Public Health.