Children are five times more likely to develop autism if they have 3 or more close relatives with autoimmune disorders like Type I diabetes, rheumatoid arthritis, hypothyroidism, or systemic lupus according to a study published in the June 2014 issue of the Journal of Pediatric Neurology. The authors hypothesize that in many cases autism results from a predisposition to develop autoimmune disorders combined with other environmental factors.
What are those other environmental factors? There appear to be several. Brain damage during birth greatly increases the risk of developing autism as does having an identical twin with the same disorder.
Other lesser but still significant risk factors include:
- Emigration to a foreign country during pregnancy, apparently because stress during pregnancy affects fetal brain development
- Experiencing a hurricane during pregnancy
- Being conceived within a year of an older sibling's birth
- Parental mental illness such as schizophrenia or depression
- Older parents--mothers older than 35 and fathers older than 40.
- Exposure to pollutants
Note, however, that less than 3% of children experiencing the adverse conditions listed above will develop autism. Therefore, any older woman who wants a child can be assured that her child will most likely not have autism, especially if she takes steps to minimize other risk factors such as prematurity and exposure to pollutants.