Study shows your anxiety may have started in the womb due to pregnancy stress

If you struggle with anxiety, the roots may trace back to before you were even born. Research has found that stressful or unhealthy conditions during pregnancy can change how a baby’s brain develops in ways that may increase their risk of anxiety later in life.

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Researchers at Weill Cornell Medicine studied mice and found that when mothers experienced infection or stress during pregnancy, their offspring grew up showing more anxious behavior. The changes weren’t in the genetic code itself, but in epigenetic programming - chemical markers that influence how genes work.

What this means is that prenatal adversity can leave lasting imprints on certain brain cells through epigenetic changes, which may explain why some people are more prone to anxiety. 

Scientists have known that problems during pregnancy can raise a child’s risk for mental health issues, but they haven’t fully understood how those experiences affect the brain.

This study, published September 10 in Cell Reports, found that the region of the brain called the ventral dentate gyrus (vDG), which helps assess threats, was affected. Some neurons in this region became “rewired” to be overly sensitive, firing too much when faced with even mild danger. This made the mice anticipate threats and avoid situations unnecessarily - aka anxiety.

To recreate stress in the womb, researchers used mice with abnormal immune activity during pregnancy. Even though the babies were genetically normal, they grew up showing anxious behavior - like avoiding open spaces and overreacting to stress. 

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To figure out why, the team looked at changes in the brain. They found that certain neurons had chemical tags, called DNA methylation, that switched genes on or off in unusual ways. These changes, known as epigenetic, don’t alter the DNA itself but change how it’s read. Thousands of these switches were different, especially in genes tied to the connections between brain cells. The most affected neurons became overactive when the mice faced threats, linking these changes to anxiety.

Dr. Miklos Toth M.D. Professor in the Department of Pharmacology at Weill Cornell Medicine, who co-led the research, explains, “Our data reveal prenatal adversity left lasting imprints on the neurons of the vDG linking gestational environment to anxiety-like behavior." “This mechanism may help explain the persistent stress sensitivity and avoidance seen in individuals with innate anxiety," he continued.

This discovery could eventually help identify biomarkers for risk and new targets for treatment, while also highlighting the importance of maternal health during pregnancy.