The place where a woman was born and raised can be a risk factor for autism in her children, according to a new study published in the journal Pediatrics.
In the U.S., children of foreign-born women tend to have a higher risk for autism, compared with children born to white American mothers.
Currently, autism reports are highest among white (non-Hispanic) children in the U.S., but these new findings show that other ethnic groups are actually at greater risk.
Using data from Los Angeles County, researchers from the University of California, Los Angeles (UCLA) found that children of foreign-born women who are black, Central or South American, Filipino, and Vietnamese had a higher risk of autism, compared with children born to white American mothers.
There were similar findings among children of U.S.-born African-American and Hispanic women.
Until now, experts have had a difficult time determining prenatal risk factors for autism other than the mother’s age and complications during pregnancy. However, recent studies have suggested a link between the nation where a woman is born and her children’s risk for autism.
“Epidemiology has a long tradition of using migration studies to understand how environmental and genetic factors contribute to disease risk in populations,” said senior author Beate Ritz, M.D., Ph.D., chair of the Fielding School of Public Health’s department of epidemiology.
“The fact that 22 percent of six year-olds born in the United States have immigrant parents opened a unique opportunity for us to consider the inﬂuence of nativity, race, and ethnicity on the causes of autism spectrum disorder.”
For the study, researchers analyzed birth records for children born in Los Angeles County who had been diagnosed with autism between the ages of three and five from 1998 to 2009. In total, 7,540 children with autism were identified from more than 1.6 million births.
Once adjusted, when compared to U.S.-born white mothers, rates were 76 percent higher in children of foreign-born black mothers, 43 percent higher in women born in Vietnam, 25 percent higher in women born in the Philippines, 26 percent higher in women born in Central or South America, and 13 to 14 percent higher in Hispanic and black women born in the U.S.
There are several reasons why the mother’s place of birth is a risk factor. One may be the psychological and physical stress suffered by the mother during relocation, for example, due to escaping war, natural disasters, or malnutrition from famine.
“For foreign-born mothers, language and cultural barriers in the U.S., and a lack of access to health care could also have caused an underestimate of autism spectrum disorder in these populations,” said Ritz, also a professor of neurology and a member of the UCLA Brain Research Institute.
“Our ﬁndings suggest that we need to do a better job of early identiﬁcation and treatment of autism spectrum disorder for these large and diverse immigrant communities who vary in risk, protective factors and access to health care.”