Maternal COVID-19 Infection Linked to Higher Autism Risk in Children, Study Finds

New Research Links Prenatal COVID-19 Exposure to Increased Neurodevelopmental Risk

A comprehensive new study suggests that children born to mothers who contracted COVID-19 during pregnancy may face a slightly higher risk of being diagnosed with autism spectrum disorder (ASD) or other neurodevelopmental disorders (NDDs) by the age of three. The findings, published by researchers from Massachusetts General Hospital (MGH) and Harvard Medical School, underscore the potential long-term impacts of maternal infection on fetal brain development.

The study, which analyzed the medical records of thousands of children born during the pandemic, found that while the absolute risk remains low, the association is statistically significant, particularly when the infection occurred early in the pregnancy.

This research provides critical data for clinicians and expectant parents, emphasizing the need for continued vigilance and preventative measures, such as vaccination, during the prenatal period.

Methodology and Key Data: Analyzing the Pandemic Cohort

The MGH and Harvard team examined the health records of over 18,000 children born between March 2020 and December 2021. Of this cohort, approximately 1,500 mothers had a documented COVID-19 infection during their pregnancy.

By tracking these children through their first three years of life, researchers were able to compare the rates of neurodevelopmental diagnoses between the exposed and unexposed groups. The analysis rigorously controlled for several confounding factors known to influence neurodevelopment, including maternal age, race, socioeconomic status, and pre-existing conditions like hypertension and diabetes.

Core Findings on Neurodevelopmental Disorders

The study revealed a clear association between maternal COVID-19 infection and subsequent diagnosis of NDDs, including ASD:

• Overall Risk Increase: Children whose mothers had COVID-19 during pregnancy had a 30% higher risk of being diagnosed with ASD or another NDD by age three, compared to children whose mothers did not have the infection.
• Timing is Crucial: The risk was not uniform across the entire pregnancy. The most significant increase was observed when the mother was infected during the first trimester.

“The timing of the infection appears to be a critical factor,” noted the researchers. “Our data suggests that the period of early fetal neurodevelopment is particularly vulnerable to the systemic effects of maternal viral illness.”

The First Trimester Vulnerability

When the infection occurred during the first trimester, a period of rapid and critical brain formation, the risk of an NDD diagnosis was found to be 80% higher. This finding aligns with existing knowledge regarding the vulnerability of the developing central nervous system during the initial weeks of gestation.

Even when the infection occurred later—in the second or third trimester—the risk remained elevated, showing a 21% higher likelihood of an NDD diagnosis. This suggests that while the first trimester is the most sensitive period, the systemic effects of the virus can potentially impact the fetus throughout the pregnancy.

Dissecting the Mechanism: Inflammation, Not Viral Invasion

One of the most important aspects of the study was ruling out common alternative explanations for NDD risk. The researchers specifically found no association between maternal COVID-19 infection and increased risk of preterm birth or low birth weight, both of which are established risk factors for neurodevelopmental challenges.

This suggests that the mechanism driving the increased risk is likely not related to these common complications, but rather to the maternal immune response itself.

The Role of Systemic Inflammation

The prevailing hypothesis among researchers is that the increased risk is mediated by inflammation. When the mother’s body fights a significant viral infection like COVID-19, it releases a cascade of inflammatory molecules (cytokines) into the bloodstream. This systemic inflammation can cross the placenta and potentially disrupt the delicate processes of fetal brain development.

This mechanism is not unique to COVID-19. Previous epidemiological studies have linked other maternal infections—such as influenza, rubella, and Zika—and the associated inflammatory response to elevated risks for NDDs.

Dr. Andrea Edlow, the senior author on the study, emphasized the need to focus future research on the specific inflammatory markers involved and the severity of the maternal illness.

“We need to understand which specific inflammatory pathways are most detrimental to the developing fetus,” Dr. Edlow stated. “This knowledge could pave the way for targeted interventions to mitigate the risk in future pregnancies.”

Context, Limitations, and Interpreting the Findings

It is crucial for readers to understand the context of these findings, particularly the distinction between association and causation, and the limitations inherent in this type of retrospective study.

Association vs. Causation

This study demonstrates an association between maternal COVID-19 infection and a higher rate of NDD diagnoses; it does not prove that the virus directly causes autism. Many complex genetic and environmental factors contribute to ASD. The findings indicate that maternal infection is one factor that may slightly increase the overall probability.

Absolute Risk Remains Low

While a 30% or 80% increase sounds dramatic, it refers to the relative risk compared to the baseline population. Because the overall prevalence of ASD in the general population is relatively low, the absolute increase in risk for an individual child remains small. This information should inform preventative health decisions, but not cause undue alarm.

Study Limitations

As with any large-scale retrospective analysis, the study has limitations that must be acknowledged:

• Diagnosis Age: The study only tracked children up to age three. Many NDDs, particularly milder forms of ASD, are often diagnosed later, meaning the true prevalence in the exposed group might be underestimated.
• Infection Severity: The study relied primarily on documented ICD codes for COVID-19 diagnosis and did not always capture the severity of the maternal illness (e.g., whether the mother was asymptomatic, had mild symptoms, or required hospitalization).
• Variant Specificity: The study covered the period from early 2020 through 2021, encompassing the original strain and early variants. It does not provide insight into the risks associated with newer variants like Omicron or subsequent strains prevalent in 2025.

Key Takeaways and Expert Recommendations for Expectant Parents

For individuals who are pregnant or planning conception, these findings reinforce the importance of minimizing exposure to respiratory viruses and maintaining optimal health throughout the prenatal period.

Practical Steps for Risk Mitigation

Based on these findings and general public health guidance, experts recommend the following actions for expectant parents:

• Prioritize Vaccination: Staying up-to-date with COVID-19 vaccination and boosters is the most effective way to prevent severe illness and reduce the magnitude of the inflammatory response, which is hypothesized to be the primary risk factor.
• Maintain General Health: Focus on managing chronic conditions (like diabetes and hypertension) and maintaining a healthy lifestyle, as these factors can also influence the inflammatory environment.
• Avoid Exposure: Continue practicing good hygiene and avoiding crowded, unventilated spaces, especially during periods of high viral transmission, particularly in the first trimester.
• Open Communication: Discuss these findings and any concerns regarding previous or current infections with your obstetrician or prenatal care provider.

The research provides a valuable piece of the puzzle regarding the long-term effects of the COVID-19 pandemic. While the findings warrant further investigation, they serve as a strong reminder that maternal health is inextricably linked to fetal development, and preventing severe viral illness during pregnancy is a critical public health goal.

Conclusion: Moving Toward Targeted Prenatal Care

The MGH/Harvard study offers compelling evidence of an association between maternal COVID-19 infection during pregnancy and a higher relative risk of neurodevelopmental disorders in early childhood. The focus now shifts to understanding the precise biological mechanisms—specifically, the role of maternal inflammation—and developing targeted strategies to protect the developing fetus.

Future research must confirm these findings in larger, more diverse populations and investigate whether specific treatments or anti-inflammatory interventions during acute maternal infection could help normalize the risk for the child. Until then, preventative measures, especially vaccination, remain the best defense for safeguarding both maternal and fetal health.

What’s Next in Research

Researchers are now focusing on longitudinal studies to track these children beyond age three and to analyze biological samples (like placental tissue and maternal blood) to identify specific biomarkers associated with the increased risk. The goal is to move beyond association and identify predictive markers that could allow clinicians to offer personalized monitoring and early intervention for vulnerable children.