A STUDY claims to have identified three maternal jobs that could raise the risk of a child’s autism.

Published today in the BMJ’s Occupational & Environmental Medicine journal, the study examined data on the jobs mums held before, during and after pregnancy to investigate any impact on the neurodevelopment of their children.

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A study has said that mums who work in high stress jobs have a greater chance of having a child with autism Credit: A study has said that mums who work in high stress jobs have a greater chance of having a child with autism

It said these higher odds also apply to mums working in jobs where they are exposed to toxic chemicals Credit: Getty

Researchers at Johns Hopkins Bloomberg School of Public Health said that: “Maternal occupations with frequent exposure to toxicants and combustion products as well as high stress occupations, could contribute to neurodevelopmental risk” – such as having autism.

They said women working in ground transportation or the military, as well as high-pressure jobs in the judicial sector, were more likely to have children diagnosed with autism.

They acknowledged, however, that the study was just “observational”, meaning “no firm conclusions” can be drawn yet.

Independent experts suggested the findings were weak and do not show that a mum’s job is a “causal factor driving differences in autism risk”.

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The study was published in the BMJ but acknowledged that it was just observational Credit: Getty

Key characteristics of autism

These are some features of autism that many people with it experience. Autism is a spectrum, so everyone shows symptoms differently.

Sensitive to senses
Autistic people can be much more or less sensitive than non-autistic people to the five main senses (sight, sound, touch, taste and smell).
This also extends to senses for balance, movement, spatial awareness and awareness of internal states, such as hunger and temperature.
Social differences
People with autism may find social interactions harder because they have difficulty; interpreting social cues; facial expressions; maintaining eye contact; recognising sarcasm.
They may find they prefer to spend time alone because social interactions can be confusing.
Autism can be verbal (someone who uses communication) or non-verbal (they use other means to communicate). People can flit between the two.
Repetitive behaviours
‘Restricted and repetitive behaviours and interests’ is often listed as a trait of autism, but the National Autistic Society says many people with the condition actually find these behaviours as positive and helpful.
It is also sometimes referred to as stimming or self-regulatory behaviour.
Examples include having a strong passion or interest in a hobby, repeated behaviours like hair twirling or rocking, and preference for routine or rules to be followed.
Emotional dysregulation
People with autism may struggle to manage feelings such as frustration, anxiety, or sadness, which could lead to a ‘meltdown’ (extreme or intense outburst of emotions) or ‘shutdown’ (withdrawal).
Source: National Autistic Society

Professor Rosa Hoekstra, a professor of developmental disabilities at the Institute of Psychiatry, Psychology and Neuroscience, King’s College London, said: “For women who would like to become a mum: please choose a job you enjoy.

“Don’t let this study put you off a career in public administration or in the judicial sector.”

Experts don’t fully understand what exactly causes autism, but evidence suggests that it may be genetic. Scientists have been attempting to identify which genes might be implicated in autism for some years.

The National Autistic Society says that autism – also known as autism spectrum disorder (AS) – is not caused by emotional deprivation or the way a person has been brought up.

There is also no link between autism and vaccines, they say, explaining that there has been lots of research on this over the years and the results have “comprehensively shown there is no link”.

The society said: “Bad science and misinformation have created myths about the causes of autism.”

So, how did researchers carry out this study?

They obtained data from 1,702 cases of autism in children in Denmark born between 1973 and 2012. These cases were matched to controls based on sex and birth year.

Mothers’ employment history was then taken from the Danish Pension Fund Registry and grouped into seven categories.

The research also took into account potential confounders, including a mum’s age, history of neuropsychiatric disorders, whether they smoked during pregnancy, and socioeconomic status.

The study found that mums who work in jobs where they are frequently exposed to toxic chemicals or experience high stress have higher odds of having a child with autism. This included:

Working in military or defence jobs before or during pregnancy increased the odds of a child being diagnosed with ASD by 59 per cent, it found.

Mothers who worked in ground transportation, where they may be exposed to combustion products, were at 24 per cent greater chance of having a child with ASD.

Finally, the study found that those working in the judicial sector before conception and during pregnancy increased the chance of their children having ASD by 59 per cent.

The research was based on data from mums and children in Denmark Credit: Getty

The study was carried out by Johns Hopkins Bloomberg School of Public Health Credit: Getty

These associations were observed for jobs held one year before conception, during pregnancy and during infancy, although associations were weakened during the child’s infancy.

The study noted limitations to the research.

Firstly, the occupations were based on “industry categories” and did not include detailed information on job titles or tasks, they said.

Researchers added that the results also may not be generalisable to populations outside of Denmark.

Prof Hoekstra, who was not involved in the research, highlighted that some of the study’s findings are based on “rather low numbers of children”.

She said: “For example, the scary sounding statistic in the press release that working in the judicial sector is associated with a 59 per cent increased likelihood of a mother’s child being diagnosed with autism is based on a sample of only 29 autistic children.” 

Professor Uta Frith, emeritus professor of cognitive development at University College London, said: “This paper is not a useful addition to our knowledge of causes of ASD.

“It is simply an example of how you can get a significant correlation between categories as long as you have large enough numbers.”

Dr Stephen Burgess, a Statistician at the University of Cambridge, said: “This study is not an experiment – it was not conducted under controlled conditions, and so it is not necessarily the case that the mother’s profession is the causal factor driving differences in autism risk.

“This finding should be seen as suggestive evidence, not definitive evidence.”