MedWire News: Research suggests that women who smoke during pregnancy are more likely to have a child with a higher-functioning autistic disorder than women who do not.
"It has long been known that autism is an umbrella term for a wide range of disorders that impair social and communication skills," said lead study author Amy Kalkbrenner (University of Wisconsin-Milwaukee, USA) in a press statement.
"What we are seeing is that some disorders on the autism spectrum, more than others, may be influenced by a factor such as whether a mother smokes during pregnancy."
Previous studies have suggested a link between tobacco exposure and autism spectrum disorders (ASDs), but results have been inconsistent.
To investigate the association further, Kalkbrenner and team collected data on the prevalence of ASDs in a cohort of 633,989 children from 11 US states, aged 8 years on average, who were born between 1992 and 1998. The prevalence of maternal smoking during pregnancy was assessed using birth certificate reports.
In total, 3315 children from the cohort were diagnosed with an ASD. Of these, 1310 had Autistic Disorder (AD), 375 had ASD-Not Otherwise Specified (NOS), 584 had ASD with co-occurring Intellectual Disability (ID), and 754 had ASD without ID.
Overall, maternal smoking during pregnancy was not significantly associated with ASD in children, with 13% of mothers from the whole cohort and 11% of mothers from the ASD group reporting that they smoked during pregnancy.
When the researchers assessed the ASD cohort according to syndrome subtype, they found that there were no significant differences in maternal smoking between children with and without ASD for all subtypes except ASD-NOS.
They calculated that smoking during pregnancy increased the risk for ASD-NOS by 26% compared with non-smoking, although this was just below statistical significance.
"The study doesn't say for certain that smoking is a risk factor for autism," explained Kalkbrenner. "But it does say that if there is an association, it's between smoking and certain types of autism," an idea that she says is worth further investigation.
"The goal of this work is to help provide a piece of the puzzle. And in this we were successful," she concluded.
The results of this study are published in Environmental Health Perspectives.
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