Proximity of Maternal Time of Immigration to Child's Birth Is Associated With Autism Spectrum Disorder With Early Learning Delay Among Immigrant Populations in the United States: Findings From the Study to Explore Early Development.

Our objective was to examine the relationship between the timing of parental US immigration and autism spectrum disorder (ASD) without early learning delay (ELD), ASD with ELD, and ELD alone among US-born children. We analyzed data from a multi-site case-control study that recruited children aged 2-5 years with ASD or non-ASD developmental disorders and same-age population controls. Parental demographics were collected from caregivers at study enrollment. Mullen Scales of Early Learning ≤ 70 was used to define ELD. Among children with a non-US-born parent (N = 1048), we used multinomial logistic regression to examine time from parental immigration to the child's birth in relation to ASD alone, ASD with ELD (ASD + ELD), and ELD alone compared to population controls. Having a non-US-born mother (regardless of the father's birthplace) versus a non-US-born father only was evaluated as a potential effect modifier. Among those with a non-US-born mother, closer proximity of maternal time of immigration to the child's birth is associated with increased odds for ASD + ELD and ELD alone. There was no significant association between years since US arrival and ASD alone. Among those with a non-US-born father only, we did not observe a significant relationship between time since paternal US arrival and ASD/ELD categories. Our study suggests that time-varying exposures among immigrant mothers may be of importance for the development of ASD + ELD and ELD alone in the offspring. These results may inform research into the etiology of ASD and ELD and ways to support immigrant women of childbearing age.