According to a large study conducted in Massachusetts: Baby whose mother was infected with COVID-19 during pregnancy They were slightly more likely to have multiple neurodevelopmental diagnoses by age 3. Most of these children had speech or motor impairments, and the association was strongest for boys and for mothers who were infected late in pregnancy.
The increase in risk per child was small, but with millions of women becoming pregnant during the pandemic, even a small increase is significant. The study does not prove that COVID-19 infection during pregnancy causes autism or other brain diseases in the fetus, but it does suggest that infection and inflammation during pregnancy may affect the baby’s brain growth. This is something scientists have seen before in other diseases. This is why we help pregnant women prevent COVID-19 and closely monitor children exposed in the womb.
Research Results
Researchers at Massachusetts General Hospital examined the medical records of more than 18,000 mothers and children born between March 2020 and May 2021, before the vaccine was widely available to pregnant women. Everyone giving birth during that period was tested for COVID-19, so the team could clearly see which pregnant women had been exposed to the virus that causes COVID-19.
About 5% of those mothers contracted COVID-19 during pregnancy. Even after accounting for differences in mothers’ age, race, insurance status, and prematurity, their children were slightly more likely to be diagnosed with a neurodevelopmental disorder by age 3 than children whose mothers did not have the infection.
This association was strongest among boys and when infections occurred in the mother’s third trimester of pregnancy. Nonetheless, most children in both groups showed typical development.
“This was a very clean group to follow,” said Andrea Edlow, a maternal-fetal medicine specialist at Mass General and one of the study authors. “Universal testing early in the pandemic allowed us to know who had COVID-19 and who did not.”
Independent authorities say COVID-19, which causes a strong immune response in some people, matches biological patterns seen in other infections during pregnancy. “COVID-19 would be a very strong candidate for this to happen because the amount of inflammation is so extreme,” said Alan Brown, a professor of psychiatry and epidemiology at Columbia University who studies maternal infection and brain development and was not involved in the study.
How can infections affect brain development?
Scientists continue to study how different infections during pregnancy can affect fetal development. Serious illnesses can cause inflammation. hinders brain growth Or you can cause premature birthThis carries its own risks.
“There has been a long history of evidence that maternal infections may slightly increase the risk of many neurodevelopmental disorders,” said Roy Perlis, vice president for psychiatry research at Massachusetts General Hospital and a co-author of the study.
Edlow’s lab is investigating how infections and inflammation can disrupt brain development. In a healthy brain, immune cells help shape developing neural circuits by removing extra or unnecessary connections, a process known as “synaptic pruning,” which sculpts the brain’s wiring. When the mother’s immune system is activated by infection, inflammatory molecules can reach the fetal brain and alter the pruning process.
animal research Edlow’s hypothesis is supported. When scientists induce inflammation in pregnant mice, their offspring often show changes in the way brain cells grow and connect, changes that can alter learning and behavior.
Why is pregnancy delayed and why do I give birth to a boy?
In Edlow and Perlis’ study, the link between COVID-19 and developmental delays was strongest when infections occurred late in pregnancy, i.e. in the third trimester. This is also the time when the fetal brain grows most rapidly, forming and refining millions of neural connections.
“When we think about organ development, we think of early pregnancy, but the brain is an exception. There is a tremendous amount of brain development in the third trimester, and this continues after birth,” Perlis said. “It is entirely plausible that the third trimester is a particularly vulnerable period for brain development.”
But not all researchers agree that the third trimester is particularly vulnerable. Brian Lee, a professor of epidemiology at Drexel University, cautioned that because most mothers in the study were tested at birth, there were simply more late-pregnancy infections to analyze. “This gives the study more power to detect differences in the third trimester,” he said. “This does not prove that early infection is not important.”
The study also found stronger effects in boys. The pattern is familiar. In general, boys are more likely than girls to have speech or motor difficulties or to be diagnosed with autism. Researchers suspect that male fetuses may be more vulnerable to stress and inflammation, although the biology is not fully understood.
What research can and cannot show
Edlow and Perlis are careful to say that the study shows a link, not evidence that COVID-19 infection during pregnancy causes developmental problems. many other factors Correlation can be explained.
Mothers with COVID-19 may have other health conditions that increase the risk of developmental delays in their children, including obesity, diabetes, and mental health conditions. “A person with mental disorder You are much more likely to get COVID-19. There are many women with mental disabilities. You are more likely to have a child with neurodevelopmental problems” Lee said. “Parents Deteriorating physical health They also have a higher risk of having a child with neurodevelopmental problems.”
According to Lee’s research Infections before and after pregnancy may also be linked to autismThis suggests that shared genetics or environment, rather than the infection itself, may be involved. That’s why experts say much larger, longer-term studies are needed to understand the extent of risk posed by infection.
Edlow, Perlis and their team plan to follow the children in the study to see if those early differences persist or disappear as they get older. They are also studying how inflammation during pregnancy affects the placenta and fetal brain, and how to counteract these effects.
What about vaccinations?
Because the study tracked pregnancies from the beginning of the pandemic, it does not answer whether vaccination changes risk. But other studies are reassuring.
A large national study in Scotland. We found no differences in early developmental outcomes. Between children whose mothers were vaccinated and those whose mothers were not. Another study from the US found the same thing: There is no association between prenatal COVID-19 vaccination and developmental delay over 18 months. Both are consistent with decades of data showing that vaccinations during pregnancy are safe for both mother and baby.
“The vaccine is given for a short period of time. It boosts your immune system and then it comes back to normal,” Edlow said. “Covid (infection) is much more persistent and unpredictable, and people can develop dysregulated immune phenomena that are not really present in the vaccine response.”
What this means for parents and clinicians
Since late 2020, confusion and misinformation about the safety of COVID-19 vaccination during pregnancy has become widespread. Some women have been hesitant to get vaccinated for fear it could harm their babies. But the evidence afterward was clear. The coronavirus vaccine is safe even during pregnancy. American College of Obstetricians and Gynecologists COVID-19 vaccination is highly recommended to protect both mother and child.
Experts say the broader lesson is that pregnancy is a vulnerable time and prevention is important. for coronaBut the same goes for other infections.
Janet Currie, a professor of economics at Yale University, said that despite decades of evidence, these risks are still underestimated. “It is recommended that pregnant women get the flu vaccine, but very few pregnant women get it,” she said. “I think doctors are reluctant to vaccinate pregnant women.”
“Protecting mothers protects the long-term health of their offspring…. The best intervention is vaccination,” said Gil Mor, scientific director of the C.S. Mott Center for Human Growth and Development at Wayne State University in Detroit.
100 year old eco
The idea that what happens in the womb can shape life after birth took root through studies of famines, such as the Dutch “winter of famine” in the final months of World War II. As the Germans blockaded the western Netherlands in 1944 and 1945, rations fell to a few hundred calories per day. Thousands of people died from starvation, and women who became pregnant during that period gave birth to babies who faced higher risks later in life. heart disease, diabetesand schizophrenia. This episode isfetal origin” The idea is that deprivation or stress during pregnancy can have lifelong effects.
that 1918 flu pandemic We extended that idea to infections. Babies exposed to influenza in utero have been shown to have small but persistent infections later in life. Difference Between Education and IncomeThis is a sign that illness during pregnancy may affect brain development. researcher taiwan, sweden, Swiss, braziland japan We found similar results. Some have argued that these findings reflect the chaos of World War I rather than the flu itself. but study later, uk and FinlandIt strengthened the case for a biological impact, emphasizing that the infection itself, rather than wartime upheaval, was the main driver.
“It’s not just the flu that can change a fetus’s neurological development,” explained Kristina Adams Waldorf, a professor of obstetrics and gynecology at the University of Washington. “Different types of infections in the mother can be transmitted as signals to the fetus, which can alter the fetus’s brain development.”
100 years later, the same question was raised again with COVID-19. Could infections during pregnancy subtly affect how children grow and learn? A new study from Massachusetts General Hospital provides an early look at this.
