Prenatal stress and ASD

There has been some very interesting research recently about how prenatal stress in the mother could contribute to the behaviour of the child. This is thought to occur at the biological level by a masking or unmasking of genetics, that affects the biological response, and ultimately the behavioural response, of the child to a particular situation. This has been demonstrated in rodent responses to fear, for example. Hence, the hypothesis has been that perhaps prenatal stress events in mothers contributes to autism in children. This has been looked at previously:
Tropical storms
Famly discord
Prenatal stress (autistic traits only)
Just published, a UK/Swedish study looked at the correlation of stressful events during pregnancy and the diagnosis of autism in children. They looked at many stressful events such as death in the family, work stress, prenancy stress, major arguments, etc. They did not find a correlation of prenatal stressful events with ASD. If prenatal stress was a major factor in a child developing ASD, then the evidence would have emerged in this study. If prenatal stress was a minor risk factor, then it may have been missed by the study. Since only acute/incidental stress events were investigated, long-term and repetitive stress events may still prove to be a major risk factor.
Randal