In The Politics of Autism, I discuss various ideas about what causes the condition.
There is a very long and growing list of other correlates, risk factors, and possible causes that have been the subject of serious studies:
A release from the University of Virginia:
Antidepressant use during pregnancy may combine with inflammation to heighten the risk of lifelong neurodevelopmental changes in babies' brains, such as those linked to autism, new research from the University of Virginia School of Medicine suggests.
A team of UVA neuroscientists found that commonly used antidepressants known as selective serotonin reuptake inhibitors (SSRIs) can interact powerfully with inflammation in the mother's body from infections or other sources. In lab mice, this interaction caused harmful changes in the placenta and the decidua – the direct connection between mother and child – and affected the developing brain.
Zengeler, K.E., et al. (2022) SSRI treatment modifies the effects of maternal inflammation on in utero physiology and offspring neurobiology. Brain Behavior and Immunity. doi.org/10.1016/j.bbi.2022.10.024.
NOTE, HOWEVER THAT ANOTHER RECENT STUDY DOES NOT FIND A RELATIONSHIP.