Eric Thayer / Reuters

Pregnant women are often told to avoid stress. Easier said than done. Work, school, life—stress is inevitable. And now researchers are saying they can even document an ill effect on babies when mothers confront one of the most unavoidable stressors: natural disasters.

In 2009, researchers from the City University of New York received a grant from the National Institute of Mental Health to better understand the impacts of maternal stress and depression on fetal development and long-term psychological outcomes for infants. Most of the 600 women enrolled in the study were low-income and ethnic minorities who were being served by major hospitals in the New York City area—a population, the study notes, that is already at high risk of complications for both mother and baby. These women have less access to prenatal care and medical support, in part because they often don’t have very good health insurance.

The study expanded in 2012, the same year that Hurricane Sandy flooded cities and towns along the eastern U.S. coast. This presented the researchers with a rare opportunity: In a study of maternal health, the scientific community widely considers it unethical to randomly impose stressful conditions on women and then measure the effects. But when the storm hit, it essentially created an experimental group and a control group of its own: pregnant women already enrolled in the study who lived through the storm, and women who gave birth just before it hit.

“The storm was horrible. The power was out and people were trapped in the basement of buildings,” says Yoko Nomura, the study’s lead author and a professor at Queens College and the Graduate Center at CUNY. “Those horrible things are really stressful. A mother can handle it, but the fetus is like a captive audience.” How babies handle stress is a lot like how they take medicine, she explains: You can give an infant certain medications, but the dosage has to be much lower. For a fetus, receiving even a small amount of stress hormones can have outsize negative effects.

Six months after giving birth, mothers were asked to report the frequency of certain infant behaviors and reactions, like laughing or smiling and sadness or fear. In line with existing research on stress, the results showed that for women who had already shown symptoms of prenatal depression, the storm exacerbated the consequences for their babies. They showed higher rates of distress and lower rates of pleasure seeking than babies born before the storm. In other words, living through the storm amplified the impacts of existing prenatal depression. The effect was moderate but significant, and the researchers do not yet know how or whether there will be longer-term consequences. While the researchers found that the effect was observable across income groups, it will take further research to understand the nuances of how this plays out across class and race, as the study sample was too small to draw those conclusions.

While it’s generally understood that stressful events during pregnancy can trigger depression, that maternal depression can affect fetuses, and that natural disasters can trigger depression or anxiety, “people aren’t connecting the dots,” says Asim Shah, a professor and the executive vice chair of the psychiatry department at the Baylor College of Medicine. Shah wasn’t involved with the recent study, but he’s worked with survivors of Hurricanes Harvey and Katrina.

“The effects of a [natural] disaster are multifaceted,” he says. In the adults Shah worked with, common responses included insomnia and anxiety. Even two or three years after Katrina, some patients experienced post-traumatic stress, which could be triggered even by normal levels of rainfall. “We don't have the tools to address trauma from hurricanes and natural disasters,” Shah says.

As climate change increases the frequency of large-scale natural disasters, lower-income mothers and women of color are likely to suffer disproportionately. After Hurricane Harvey in 2017, low-income families were more likely than the affluent to live in damaged and dangerous housing; one expectant mother profiled by the Texas Observer was encouraged to induce birth early to treat her baby for mold exposure. Either way, she would eventually bring her child home to walls filled with mold and allergens, putting the baby’s health at risk. And a recent NPR report found that wealthy, white families who own homes in relatively safe neighborhoods were far more likely to receive federal aid from FEMA than lower-income families of color who rent homes in more environmentally vulnerable neighborhoods. As a result, existing inequalities are exacerbated, which could have profound consequences for public health specifically, and maternal health generally.

After any traumatic event, getting back to a sense of normalcy can be a key step toward reducing the psychological toll. “If your house is destroyed in a hurricane and you're able to make it and rebuild with insurance, your trauma would be negligible if you're back to functionality, as opposed to a person who lost everything and doesn't have the means to rebuild a house,” Shah says. “They will be suffering for months or years.” But Shah adds that identifying a problem is often the first and most important step. “People might think it’s normal to feel anxious and stressed in pregnancy,” he says. That might stop families from seeking treatment or medication for new mothers and their children, especially if the effects of the stress manifest years after a natural disaster struck. “We have to counsel [families], and with therapy and treatment we can make the outcomes better.”

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