It appears that certain babies are born with a genetic vulnerability to autism that is then triggered by something in the external environment, either while he or she is still in the womb or sometime after birth.
Prenatal factors that may contribute to autism
- Taking antidepressants during pregnancy, especially in the first 3 months
- Nutritional deficiencies early in pregnancy, particularly not getting enough folic acid
- The age of the mother (children born to older fathers also have a higher risk of autism)
- Complications at or shortly after birth, including very low birth weight and neonatal anemia
- Maternal infections during pregnancy
- Exposure to chemical pollutants, such as metals and pesticides, while pregnant