American researchers have said that their recent study suggests children born to mothers infected with Covid-19 during pregnancy faced a higher risk of autism, along with other neurological differences such as delays in speech and motor development, reports The Washington Post.
This new analysis – of more than 18 100 births in Massachusetts, published in the journal Obstetrics and Gynaecology – is among the largest studies to date examining children born to women who contracted the virus starting in the early months of the pandemic until 2021, before vaccines were widely available.
The authors emphasised that, as an observational study, the findings do not prove that Covid-19 causes the conditions diagnosed in children, but rather, signal an association between maternal infection and these outcomes. And the risk of such a diagnosis, even while elevated for women, remains extremely low, said Andrea Edlow, a Physician Scientist at Mass General Hospital and an associate Professor of Obstetrics and Gynaecology at Harvard Medical School.
“It’s not that every pregnant woman with Covid-19 in pregnancy needs to think that her child is going to have autism,” Edlow, a co-author, said. “Overall, the absolute risk is not extremely high.”
Vaccines important
Public health experts say the findings underscore the importance of Covid-19 vaccination during pregnancy, and that protecting expectant mothers helps safeguard both their health and that of their babies. The results come at a time when coronavirus vaccination rates have declined.
Earlier this year, Health Secretary Robert F. Kennedy Jr announced that the Centres for Disease Control and Prevention (CDC) would no longer recommend the vaccine for healthy pregnant women, prompting widespread criticism from public health experts.
The American College of Obstetricians and Gynaecologists continues to recommend vaccination, and federal officials now say all Americans regardless of risk factors should consult a medical provider about getting a Covid vaccine.
Mary Ann Comunale, an associate Professor at Drexel University’s College of Medicine, said the study offers important evidence-based information for discussion between a clinician and their patient.
“This is particularly important in the current climate of vaccine hesitancy,” said Comunale, who was not involved in the Massachusetts study.
In the new study, researchers examined medical records between 1 March 2020 and 31 May 2021. Among 861 women who had tested positive for the coronavirus during pregnancy, 140 gave birth to a child who would receive a neurodevelopment diagnosis by the age of three.
Few had received vaccinations, researchers said. Future studies of larger populations are needed to reveal the potential risk for women who received coronavirus vaccinations, said Edlow and co-author Roy Perlis, a Mass General researcher and Harvard Psychiatry Professor.
The research builds on a growing body of work about the impact of viral infection during pregnancy and foetal health. There’s strong evidence that some viruses such as rubella, varicella-zoster and Zika may directly cause foetal injury.
In 2015 and 2016, the World Health Organisation declared a public health emergency when the Zika virus was spreading in Latin America and was linked to hundreds of births of children with microcephaly, a condition characterised by an abnormally small head and under-developed brain.
Scientists believe it is rare for respiratory viruses such as flu and SARS-CoV-2, which causes Covid-19, to cross the placental barrier and that the impact on the foetus may be because of a mother’s immune response.
One possible culprit may be inflammation, which results in the release of signalling molecules that may influence how neurons – the working unit of the nervous system – in the brain grow, connect and migrate.
Flu and Covid-19 have been linked to obstetric complications such as preterm birth but the evidence regarding longer-term impacts on children’s neurodevelopment has been more mixed, with some studies showing small increases in diagnoses and others showing no effect.
“If the foetus’ immune system gets really revved up, that could have downstream consequences, not just for the developing brain, but also for the metabolic system, the liver, the pancreas, the heart, the adipose tissue,” said Edlow.
She added that in addition to neurodevelopmental diagnoses, that could lead to obesity and metabolic syndrome or insulin resistance later in life.
Researchers noted several weaknesses in the study. Lisa Croen, senior research scientist at the Kaiser Permanente Northern California Division of Research, said that maternal conditions like obesity, hypertension, gestational diabetes were not controlled for in any of the analyses “so findings could be confounded by these factors”.
She said more research is needed but the results do “provide additional, strong rationale for supporting Covid-19 vaccination in pregnancy”.
Study details
Neurodevelopmental Outcomes of 3-Year-Old Children Exposed to Maternal Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Infection in Utero
Shook, Lydia; Castro, Victor; Ibanez-Pintor, Laura; Perlis, Roy; Edlow, Andrea.
Published in Obstetrics & Gynaecology on 30 October 2025
Abstract
Objective
To determine whether in utero exposure to maternal severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is associated with increased risk of adverse neurodevelopmental outcomes in children by age 3 years.
Methods
We conducted a retrospective cohort study of 18,124 live births to individuals who delivered between March 1, 2020, and May 31, 2021, within the Mass General Brigham health system. The exposure of interest was maternal SARS-CoV-2 infection, defined as a positive SARS-CoV-2 polymerase chain reaction test result during pregnancy. The outcome of interest was presence of any neurodevelopmental diagnosis up to 36 months after birth, identified using International Statistical Classification of Diseases and Related Health Problems, Tenth Revision diagnostic codes. To evaluate the association between SARS-CoV-2 exposure in pregnancy and these diagnoses, we used logistic regression models adjusting for maternal age, race and ethnicity, insurance type, hospital type, and preterm birth.
Results
Among the 861 individuals with SARS-CoV-2-exposed pregnancies (4.8%), 140 offspring (16.3%) received a neurodevelopmental diagnosis by 36 months after birth, compared with 1,680 of 17,263 unexposed offspring (9.7%) (unadjusted odds ratio 1.80, 95% CI, 1.49–2.17; adjusted odds ratio [aOR] 1.29, 95% CI, 1.05–1.57, P=.01). In sensitivity analyses, largest effects were observed in third-trimester exposures, overall (aOR 1.36, 95% CI, 1.07–1.72, P=.01), and among male offspring (aOR 1.43, 95% CI, 1.05–1.91, P=.02).
Conclusion
Maternal SARS-CoV-2 infection in pregnancy was associated with increased risk of adverse neurodevelopmental diagnoses by age 3 years, with effects most pronounced after third-trimester exposure and in male offspring. These findings highlight the importance of long-term neurodevelopmental monitoring for SARS-CoV-2–exposed children.
See more from MedicalBrief archives:
Milestone delays in babies exposed to Covid in womb – US cohort study
Pregnant women pass Covid antibodies to their babies — Weill Cornell
Covid doubles perinatal risk in pregnancy – Large Kaiser study
Maternal Covid infection increases preterm/low birth/stillbirth rate in unvaccinated women