Associations of Characteristics of Parental Country of Birth with Autism Spectrum Disorder and Early Learning Delay Among Immigrant Populations in the US: Findings from the Study to Explore Early Development.

The study is observational, so it can show association but not cause. Some outcome groups were small, which limited adjustment and power to detect differences for autism alone and early learning delay alone. Country index scores were split into only two groups, so dose-response relationships could not be examined. Intellectual disability cannot be reliably diagnosed before age 5, so early learning delay was used as a proxy and may misclassify children. The exposures were country-level indices, not individual data on migration stress, refugee status, poverty, violence, trauma, or post-migration supports. The sample was not representative of all US immigrant families; some countries were overrepresented, and families needed to communicate in English or, at two sites, English or Spanish. Immigrant families may differ from non-immigrant families in ways not measured, including resources, education, and access to diagnosis.

The authors reported no known conflicts of interest.

Do not conclude that parents' country of birth or human development causes autism plus early learning delay. The study measured country-level indices, not individual stress, nutrition, infection, diagnosis access, or genetic factors.