Pregnant women exposed to high levels of air pollution are twice as likely to have a child with autism as women who lived in low pollution areas, a study has found.
US scientists found that the risk was doubled for women living in the most polluted locations.
For the study, researchers identified 325 women who had a child with autism and 22,000 who had children without the disorder.
Data collected was used to assess pollution exposure in the areas where the women lived.
The scientists found a clear link between being pregnant somewhere with high levels of pollution and having an autistic child. Diesel and mercury pollution showed the strongest link.
Women living in the top fifth of locations with the highest levels of these pollutants were twice as likely to give birth to a child with autism as those in areas with the lowest levels.