New research has shown that maternal illness during pregnancy does not increase the likelihood of a being diagnosed with autism, despite many previous studies reporting a link. Recently published in Nature Medicine, researchers from NYU Grossman School of Medicine at New York University Langone Health, Drexel University’s A.J. Drexel Autism Institute and Aarhus University in Denmark suggested that the few conditions that were truly associated with autism were actually complications with the fetus. Consequently, these complications in the fetus may be early signs of autism in the child and not the cause of it.
Diana Schendel, PhD, leader of the Modifiable Factors in Autism program in the Autism Institute and co-author of the study, shared her insight on the study’s findings with the Drexel News Blog.
What is the biggest takeaway from this research?
While many studies have reported a link between a mother’s health during pregnancy and autism in her child, our new study shows that nearly all of the links are not because the mother’s condition caused the autism. Instead, the links need to be explained by looking at other factors shared in the family, such as genetics, exposure to pollution, or access to health care.
Was there anything in the findings that surprised you?
We were surprised at the number of maternal conditions where the link with autism seemed to be explained by family factors – that is, things shared in the family that we may not have measured for the study – rather than by the mother’s condition during pregnancy specifically.
For example, we compared siblings – where the mother had the condition in one pregnancy, but not another – and we also compared fathers and mothers with the same condition. In both types of comparisons, the link between many conditions and autism was the same between siblings, or regardless if it was the father or the pregnant mother with the condition. Both comparisons suggest that the link to autism is something shared in the family rather than just in the mother alone.
Overall, we were very careful to analyze the data in many different ways to check our results, but we saw similar results each way, which was surprising.
How was maternal medical history examined?
For the study we collected information on the medical histories of mothers for more than 1.1 million pregnancies (among 600,000 mothers) from nation-wide health databases in Denmark.
Unlike medical records in the United States, which are scattered across many different medical providers that a person sees during their lifetime, in Denmark all of an individual’s health records beginning in the 1970s from inpatient admissions to public hospitals, plus records from specialist outpatient clinic visits beginning in the 1990s are consolidated into central databases linked by each person’s unique government-issued number.
Following strict security measures, researchers can access these data for approved research purposes. With these data we were able to check each mother for more than 1,700 distinct diagnoses, as well as autism diagnoses in their child, as defined by international diagnosis coding standards called ICD-10 codes. From these, we focused our analysis on 236 diagnoses, including ones that occurred in a relatively small proportion of pregnancies.
Why are these findings important?
While our results suggest that maternal conditions in pregnancy are not directly linked to autism, our findings should not change the ways that professionals and parents practice optimal care and health promotion during pregnancy.
All of the maternal conditions we studied may impact a pregnancy, or development in the child, in many ways apart from autism and therefore should be prevented or carefully monitored as always. Our findings, however, do offer a new perspective into maternal health and autism that sets the direction for future research into the complex processes involved in neurodevelopment. And a better understanding of neurodevelopment will lead us to more effective ways to support autistic children and their families.
What comes next?
Future work needs to check our findings in other settings, e.g., in different heath care systems, and with analyses that we couldn’t carry out because the size of our sample was too small. Future work also needs to dig much more deeply into the likely factors, like genetics or environmental factors, shared in the family that explain the links between family health and autism.
Reporters interested in speaking with Schendel should contact Annie Korp, assistant director, News and Media Relations, at 215-571-4244 or amk522@drexel.edu.
