These risk factors related to gene and environmental interactions include:

1. Air pollution: Mother when exposed to any sort of air pollution in form of smoke, traffic pollution, cigarate smoke, exposure to any sort of chemicals, pesticides, etc. may increase the risk of ASD.
2. Medications: If mother has been on any sort of medications during or before pregnancy which includes, antihypertensive, antidepressants, antiepileptic drugs, etc. These drugs have a direct effect over the neurodevelopmental outcome fo the newnborn.
3. During gestation or at time of birth: Premature birth, LBW, Maternal Diabetes, Preclampsia, Infections ( m/c UTI ) all these factors increases the risk of autism in child.
4. Age of Parents: Advanced parental age of the mother /father increases the risk of ASD in subsequent

Environment itself has a definite role to play in Autism but always in addition with genetic factors.