Children exposed to hyperemesis gravidarum in-utero are more likely to be diagnosed with autism spectrum disorders than those whose mothers did not have the condition, according to a study.

The findings provide additional evidence that the intrauterine environment has a “significant impact” on autism spectrum disorder risk, say Dr Darios Getahun, of Kaiser Permanente Southern California, US, and colleagues

They looked at 469,789 children born in 1991-2014 at Kaiser Permanente Southern California hospitals, 1.8% of whom were diagnosed with autism spectrum disorders.

The incidence of the disorder among unexposed children was 1.71/1,000 person-years, while it was 2.87/1,000 person-years for children exposed to hyperemesis gravidarum.