It is well known that the child’s preterm birth and low birth weight are risk factors for autism. A new study by the Yale School of Public Health offers a significant evidence that autism spectrum disorder risk factors can span multiple generations.
According to the study, parents born very prematurely were nearly twice as likely to have children with an autism spectrum disorder.
Senior author Zeyan Liew, assistant professor in the Department of Environmental Health Sciences, said, “These findings can help spark further research into the underlying mechanisms of autism risk transmission in families.”
“This is the first study to show that parental preterm birth and low birth weight might carry some risk for their future offspring as well.”
Scientists evaluated data collected from families across Denmark from 1978 to 2017 as part of its central medical records database. They linked the parents’ birth records to the medical records in their offspring to investigate whether there is a link between the parents’ neonatal characteristics and autism spectrum disorder risk in their children.
Their results suggest that women and men who were born at less than 37 weeks or low birth weight were more likely to have children diagnosed with autism spectrum disorder than those without adverse birth characteristics. The study authors reported that some other possible multigenerational risk factors they analyzed, such as grandparents’ education, place of residence, and age at the time of pregnancy, only contributed minimally to the observed associations.
Liew said, “It remains unclear how exactly autism spectrum disorder risks travel across generations, but I have some hypotheses. For one, there has been growing evidence showing that changes in gene activity in response to environmental stimuli could be inherited across generations without changing the underlying DNA sequences — a phenomenon known as epigenetic inheritance.”
“These adverse characteristics at birth may act as a proxy measure of possible heritable epigenetic modifications as a result of harmful prenatal exposures affecting early life growth, which could help explain the multigenerational transmission of disease risk we observed.”
Parents born with some unfavorable characteristics likely had to deal with challenges in the physical, mental, reproductive, or social domains of health in childhood and adulthood. When scientists evaluated these factors, they found that the parents’ educational achievement and mental health status before pregnancy played a small mediating role in the observed associations.
Scientists think the need for further research to see if the same conclusions hold in other parts of the world and other populations, with additional considerations of potential methodological challenges of conducting multigenerational studies like this.
Liew said, “From previous studies, a lot of the findings that we’ve seen in Denmark hold up in other countries as well. We think that this is not specific to Denmark, but we need more evidence from other places.”
- Jingyuan Xiao et al. Associations of parental birth characteristics with autism spectrum disorder (ASD) risk in their offspring: a population-based multigenerational cohort study in Denmark. DOI: 10.1093/ije/dyaa246