By Harshit, BOSTON, Nov. 1, 2025
Children whose mothers contracted COVID-19 during pregnancy appear to face a significantly higher risk of autism and other neurodevelopmental disorders, according to new research from Massachusetts General Hospital. The findings add to growing evidence that maternal infections may have long-term effects on fetal brain development, particularly when they occur late in pregnancy.
Study Overview and Key Findings
The study, published Thursday in the journal Obstetrics and Gynecology, analyzed more than 18,000 births within the Mass General Brigham health system between March 2020 and May 2021. Researchers compared medical records of children born to mothers who had laboratory-confirmed COVID-19 infections with those whose mothers did not test positive during pregnancy.
The results were striking: children born to infected mothers were 1.3 times more likely to be diagnosed with neurodevelopmental disorders — including autism, speech delays, and motor function disorders — by age 3.
Specifically, 16% of children exposed to COVID-19 in utero were diagnosed with a developmental disorder, compared with less than 10% in the control group.
Among those affected, 2.7% were diagnosed with autism spectrum disorder, compared to 1.1% of children born to uninfected mothers.
Impact of Timing and Gender Differences
The risk was most pronounced in boys and in cases where mothers contracted COVID-19 during the third trimester of pregnancy — a critical period for fetal brain growth. According to the study authors, previous research suggests that male fetal brains may be more vulnerable to maternal immune system responses triggered by infections.
“These findings highlight that COVID-19, like many other infections in pregnancy, may pose risks not only to the mother but to fetal brain development,” said Dr. Andrea Edlow, senior author and maternal-fetal medicine specialist at Mass General Brigham. “They also support the importance of preventing COVID-19 infection during pregnancy.”
Possible Biological Explanations
The researchers noted that the new results are “particularly notable in light of their biological plausibility.” Maternal infections can trigger inflammatory responses and immune reactions that affect fetal neural development, even if the virus itself does not cross the placenta.
“The findings build on previous research identifying potential pathways through which maternal COVID-19 infection could influence the developing brain,” said Dr. Lydia Shook, lead author and maternal-fetal medicine specialist at Massachusetts General Hospital. “Parental awareness of these risks is key so that children can receive early evaluations and support if needed.”
Context: Rising Autism Rates in the U.S.
According to the U.S. Centers for Disease Control and Prevention (CDC), about 1 in 31 children in the U.S. were diagnosed with autism by age 8 in 2022 — up from 1 in 36 in 2020. Experts say this increase largely reflects improved awareness and screening, though environmental and biological factors remain under investigation.
Earlier this year, the U.S. Department of Health and Human Services (HHS) launched a nationwide research initiative to better understand the causes behind rising autism diagnoses.
However, public discussions have at times been controversial. In September, President Donald Trump, alongside HHS Secretary Robert F. Kennedy Jr., claimed that acetaminophen (Tylenol) use during pregnancy could increase autism risk — a statement that contradicts decades of research showing no proven link between the two. Kennedy has also been criticized for promoting vaccine-related autism theories, which experts have repeatedly debunked.
Vaccination and Study Timing
Because the study analyzed births from the early phase of the pandemic — before vaccines were widely available — about 93% of mothers in the study were unvaccinated. This timing allowed researchers to isolate the effects of the infection itself, rather than vaccine interactions. Strict hospital protocols also minimized unreported COVID-19 cases.
The researchers emphasized that their findings reinforce the importance of infection prevention and vaccination during pregnancy, noting that vaccine hesitancy remains a growing concern.
“Public trust in vaccines is fragile,” Dr. Edlow said. “Studies like this underline why protection against infections — including COVID-19 — is vital for both maternal and child health.”