Study finds no causal link between maternal health in pregnancy and autism risk

In a recent interview with Contemporary OB/GYN, Magdalena Janecka, PhD, an associate professor at NYU Grossman School of Medicine in the department of child and adolescent psychiatry and population health, discussed her study on the relationship between maternal health during pregnancy and autism risk in offspring.

Two key findings were reported from the results. First, the study found that maternal diagnoses during pregnancy, such as asthma or depression, are associated with a slightly increased likelihood of having a child with autism. However, the absolute risk remains small. For example, women with such diagnoses may have a 50% higher relative risk, but this translates to an increase from a baseline of approximately 2.5% to only 3.75%, fewer than 4 in 100 women.

Second, the study provided strong evidence that these associations are not causal. The research found that women who had a certain diagnosis in one pregnancy but not in another still had children with similar autism risks across both pregnancies. Furthermore, paternal diagnoses were just as strongly associated with autism risk as maternal diagnoses, despite fathers having minimal direct biological impact after conception. These findings suggest that maternal health conditions during pregnancy do not directly cause autism, but co-occur with other underlying factors, likely genetic in nature.

Regarding prior studies, Janecka acknowledged that familial confounding is a complex issue that is often difficult to detect and address. Some earlier studies may have reported correlational links without fully accounting for these confounders. Her research examined a wide range of maternal diagnoses rather than focusing on specific conditions, revealing the widespread nature of such confounding.

Janecka also discussed the implications of these findings on autism research. While maternal health conditions during pregnancy are unlikely to be direct causes of autism, familial factors that contribute to both maternal health and autism risk still need to be investigated. According to Janecka, future studies should explore whether these factors are genetic or non-genetic and determine the precise mechanisms by which they influence autism risk.

For clinicians advising pregnant women concerned about autism risk, Janecka emphasized the importance of distinguishing correlation from causation. She encouraged putting risk statistics into context, ensuring that women understand the actual magnitude of risk increases. For example, a reported 50% increase in risk may sound alarming, but when placed in absolute terms, the change remains relatively minor. The key takeaway for clinicians is to help expectant mothers make informed decisions without unnecessary anxiety.

Overall, the study underscored the need for a nuanced approach in interpreting autism risk factors, shifting the focus from maternal health conditions themselves to the broader familial factors that may contribute to autism development.