Stress during pregnancy may harm fetal brain development

Last modified January 7, 2021. Published December 25, 2020.
A woman cradles her pregnant belly. (Cassidy Rowell, Unsplash)

A woman cradles her pregnant belly. (Cassidy Rowell, Unsplash)

When gestating mothers experience anxiety, it may affect brain development in their fetuses, scientists at Children’s National Hospital in Washington, D.C., have found.

Their study, published in JAMA Network Open last month, underscores the importance of screening women for mental health issues and equipping them with resources to help them deal with any stressors, the researchers say.

“During pregnancy, we pay a lot of attention to what’s happening to the mother physically, and of course that’s very important for the health of the child,” said Josepheen De Asis-Cruz, a staff scientist at the hospital who contributed to the research. “But I think what this study emphasizes is that the mother’s maternal health is also important, as that also may influence the child’s brain development.”

Up to half of women report symptoms of stress, depression or anxiety during pregnancy, the study notes. At the same time, emerging evidence over the last few years has shown that what happens in utero affects the long-term brain function of children.

A number of neurobehavioral studies have shown that children whose mothers experienced high stress levels had some emotional or cognitive issues. The Children’s National Hospital researchers, meanwhile, showed in a previous study that fetal brain growth of some structures such as the hippocampus lags in fetuses whose mothers experienced a high degree of stress.

The authors behind the latest research say their findings provide additional evidence that what happens in utero may impact what happens in the children’s brains over the long term.

For the study, scientists examined developing neural circuitry in fetuses at different developmental stages in 50 women between weeks 24 and 39 of their pregnancies using resting-state functional magnetic resonance imaging, or rs-fMRI. They then compared the brain scans with the results from questionnaires that screened for stress, anxiety and depression, considering both anxiety related to personality tendencies and anxiety in specific adverse situations.

“What we showed is an association with maternal anxiety levels and the strength of brain connections, as measured using MRI,” De Asis-Cruz said. 

Women who scored higher for either type of anxiety had a higher likelihood of carrying fetuses with stronger brain connections in areas important for arousal and sensorimotor skills, and weaker connections in areas involved in executive and higher cognitive functions necessary for concentration and paying attention.

“For us to be able to establish a connection, a sort of cause and effect relationship, I think that would require a longitudinal study where we follow these babies,” De Asis-Cruz said.

Now that the researchers have shown the effects during the fetal period, they will track the children during the newborn period and as they grow. Scientists are following them for 18 months to make neurobehavioral assessments that examine social, cognitive and physical development.

In the next phase of research, the scientists hope to distinguish between pre- and postnatal effects. It’s a challenging issue, De Asis-Cruz said, but following the children at different points in their brain development will help them tease out the complex relationship between what happens before birth and what happens after.

In another part of the multifaceted research into improving mothers’ health and optimizing babies’ development, researchers are studying the effect of behavioral therapy and stress management such as meditation in alleviating stress in pregnant women.

“Establishing a direct effect of what the women are experiencing right now and the long-term outcomes of the babies will take time; it is a process,” De Asis-Cruz said. “What we’re showing right now is a relationship. But I think there's no harm in trying to address the maternal issues of pregnant women right now.”

While people typically think of pregnancy and giving birth as a joyful time for both mother and families, the study illustrates how it can be a trying time for women, as well, she said.

“The more immediate goal is to raise awareness that there are changes that happen in the brain that are related to the stressors that are experienced by the mother,” De Asis-Cruz said. “This is not only true for anxiety, because other studies have shown stress also impacts the development of brain structures, and also brain function.”

The study “Association of Prenatal Maternal Anxiety With Fetal Regional Brain Connectivity,” published in JAMA Network Open on Dec. 7, was authored by Josepheen De Asis-Cruz, Children’s National Hospital; Dhineshvikram Krishnamurthy, Children’s National Hospital; Li Zhao, Children’s National Hospital; Kushal Kapse, Children’s National Hospital; Gilbert Vezina, Children’s National Hospital; Nickie Andescavage, Children’s National Hospital; Jessica Quistorff, Children’s National Hospital; Catherine Lopez, Children’s National Hospital; and Catherine Limperopoulos, Children’s National Hospital and George Washington University.

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