Study details and findings

For the study, researchers analyzed data from 224,353 children in the Kaiser Permanente Northern California health system who were born between 2010 and 2017. Of the children in the study, 5,488 were diagnosed with autism. The mean age at diagnosis was three years, and the mean maternal age at delivery was 31.9 years.

They also assessed 25 maternal diagnoses previously linked to autism. The diagnoses included pre-eclampsia, diabetes, overweight or obesity, eating disorders, different injuries, and more. Mothers in the study had a median of two conditions, with 53.4% having two or more conditions and 10.7% having five or more conditions.

Overall, 2.4% of children in the study were diagnosed with autism, with slight differences in prevalence across ethnic racial and ethnic groups. The prevalence of autism was 3.2% among Black children, 2.9% for Asian and Pacific Islander children, 2.5% for Hispanic children, and 2% for white children.

Although the researchers found that all maternal health conditions evaluated in the study were consistently associated with autism, some conditions had greater associations depending on the racial and ethnic group. Specifically, four conditions — maternal overweight and obesity, depression, asthma, and pregnancy complications — had stronger associations with autism in white mothers than Black, Hispanic, or Asian and Pacific Islander mothers.

According to the researchers, this difference could be due to disparities in healthcare access, diagnostic practices, or unmeasured environmental and genetic factors.

Commentary

According to CDC data, autism affects one in every 31 children by the age of 8 in the United States, with patterns changing among girls and children from racial and ethnic minority groups. Although several different factors may contribute to the rise in autism diagnoses, the cause of the condition is still not known.

In an accompanying editorial, Aisha Dickerson, from the Johns Hopkins Bloomberg School of Public Health, wrote that "[w]ith several maternal health conditions identified as associated with increased autism spectrum disorder in offspring, determining the reasons underlying these associations and identifying populations most impacted has garnered interest."

Dickerson added that the study's findings support the hypothesis that mothers from historically marginalized groups may experience healthcare disparities and have lower diagnostic ascertainment for adverse health conditions.

"Overall, this study not only highlights a continued need for achieving equity in healthcare access but also suggests the mother-child race-identity paradigm deserves more consideration," she said.

Magdalena Janecka, one of the study's authors from the NYU Grossman School of Medicine, also highlighted the potential for disparities to affect risk factors for autism. "Most studies examining potential risk factors for autism assume that these effects are the same across different population groups, even though we know that there is a lot of room for variation," she said.

For example, with maternal depression, "women with limited access to healthcare, or women from ethnic minority groups, may find it harder to get a diagnosis and as a result have a more severe form of disorder upon diagnosis, or they may receive different medications once diagnosed," Janecka said.

"Rather than averaging these effects across groups, we decided to start unpacking this variation," Janecka said. "Our study explores race and ethnicity as one of the factors that could change what, for example, maternal depression means as a risk factor — but many other dimensions still need to be explored, like insurance status."