Clinical research: Maternal stress doesn't trigger autism
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No concern: A large study contradicts reports that women who experience stress during pregnancy have an increased risk of having a child with autism.
Experiencing a stressful event, such as the death of a family member or a severe illness, during pregnancy does not increase the risk of having a child with autism, according to an epidemiological study published 13 June in PLoS One1.
The results contradict previous findings suggesting that maternal stress is a risk factor for autism.
Some studies have found associations between autism and factors such as tropical storms, family discord and women’s self-reports of stress during pregnancy2,3. Animal studies have shown that exposing pregnant mice to sources of stress, such as the scent of predators, is linked to changes in the brain chemistry of their offspring.
In the new study, researchers used data from two large epidemiological groups: the Stockholm Youth Cohort (SYC), which includes 589,114 children from 0 to 17 years, and the Avon Longitudinal Study of Parents and Children (ALSPAC), which follows the children of 14,541 women in Bristol, England, born from April 1991 to December 1992.
The mothers of the 4,429 children with autism from the SYC were no more likely than controls to have experienced a stressful event during pregnancy such as the death of a friend or family member, a serious accident or injury, or the diagnosis of a serious illness, the study found.
Likewise, the 72 mothers of children with autism in ALSPAC were no more likely than 11,554 others to self-report events — such as moving, losing a job or being physically or emotionally abused by a partner — that significantly affected them.
A slight association between stress and having a child with autism might need an even larger study size to become apparent, the researchers say. It is also possible that chronic stress over a long time may have a larger effect than the types of acute stress investigated in the study.
References:
1: Rai D. et al. PLoS One 7, e38893 (2012) PubMed
2: Kinney D.K. et al. J. Autism Dev. Disord. 38, 481-488 (2008) PubMed
3: Beversdorf D.Q. et al. J. Autism Dev. Disord. 35, 471-478 (2005) PubMed
Comments
Interesting study - Swedish prevalence of autism was .9% in the full cohort whilst in the UK cohort a significant difference .62%
What was interesting was this ...
ASD w/o Intellectual Disability during pregnancy adjusted OR 1.21 (0.67–2.20)
ASD with Intellectual Disability during pregnancy adjusted OR - 0.47 (0.17–1.31)
Once again this further evidences that there are distinct pathways (phenotypes) to the endpoint that is diagnosed as ASD. It would seem that 30 - 50% follow an immune system pathway.
It would not be correct to assume based on this study alone that maternal prenatal stress plays no role as an environmental factor in autism. Too many previous studies have pointed in the opposite direction. The discussion of the paper discusses this rather well.
First, the authors acknowledge the statistical limitations of their sample size. Second, the authors cite a considerable body of previous work linking stressful events with ASD outcomes. For example, as they write of several previously discovered factors: "It should be noted that both stressful migration (and subsequent period of settlement) and socioeconomic stressors are likely to be relatively chronic stressors. It is therefore possible that the acute life events included in the present study do not have sufficient or sustained enough effects to impair foetal neurodevelopment."