Climate change is a growing threat to mental health, particularly in the aftermath of severe storms, floods or wildfires, when victims can develop post-traumatic stress disorder. Now, scientists are wondering if climate-related mental health problems developed during pregnancy can be passed on from one generation to the next.
The early answer appears to be yes.
It may sound unusual, but it’s not. Researchers long have recognised that environmental and other external factors can cause genetic changes in utero, the study of which is called epigenetics.
One of the most dramatic examples of this occurred after the Dutch Hunger Winter of 1944 to 45. The children of mothers who were pregnant during the famine developed a biological response, prompting them to eat as much food as possible. Later on, they became susceptible to metabolic disorders, heart disease, obesity and diabetes, affecting multiple generations.
Similarly, pregnant people already suffering from depression who then experience the trauma of a perilous storm could pass on that trauma to their children and future generations—an ominous legacy of the hurricanes, floods, drought and heat waves that have become more frequent or intense in recent years as a result of climate change.
“It’s important to realise that the effects of extreme climate changes and natural disasters might not be transient,” said Patrizia Casaccia, director of the neuroscience initiative at the Advanced Science Research Center at the Graduate Center of The City University of New York (CUNY). “They could have long-term consequences on the developing brain by changing the way genes are regulated and resulting in increased susceptibility to psychiatric disorders.”
Prenatal depression increases the risk for infants to have a difficult temperament, but when we factored in the stress of experiencing an environmental catastrophe, one plus one was not two. It was ten.
Yoko Nomura, professor, City University of New York and Queens College
Immediately after Superstorm Sandy hit New York in October 2012, Queens College opened its auditorium as a shelter for those displaced by the hurricane. Yoko Nomura, a psychology professor with CUNY’s graduate center and Queens College, recognised several of the pregnant people staying there as subjects in a study she already had underway on pregnancy and stress. She and her colleagues decided to find out whether the ordeal of having survived Sandy also affected their babies.
“Hurricanes and other natural disasters are becoming more frequent,” she said. “It is unquestionable that [we need] more studies to fully understand the impact of these environmental stressors on the mental health of future generations.”
The results were disturbing. She and her colleagues found that climate change presents an exponentially greater danger for children born to mothers suffering from prenatal depression. Exposure to a natural disaster, in this case, Sandy, radically increased the likelihood that the babies would be fearful and distressed. The study appears in the journal Infant Mental Health and builds upon previous studies that suggest prenatal stress can have negative effects on an infant’s temperament.
“Prenatal depression increases the risk for infants to have a difficult temperament, but when we factored in the stress of experiencing an environmental catastrophe, one plus one was not two. It was ten,” Nomura said. “Our research found that, compared to other babies, infants born to women who were prenatally depressed and pregnant during Superstorm Sandy had higher rates of distress.”
The study enlisted 310 pairs of mothers and children, recruited from clinics that serve patients from around New York City. The researchers assessed the symptoms of depression in mothers, and mothers reported the temperaments of infants via a questionnaire six months after birth.
The babies of depressed mothers showed more distress and fear, less smiling and laughter, and less “soothability” and cuddliness than those of mothers who weren’t depressed. The babies of depressed mothers who were pregnant during Sandy showed even worse temperaments, according to the study.
The researchers theorise that epigenetic responses to maternal trauma could be the reason for the distress in infants. “The combination of environmental stressors and biology may compromise gene expression and cause an excessive amount of cortisol to be passed from the mother to the fetus, resulting in infants having poorer emotional regulation, shyness and fearfulness,” said Jessica Buthmann, a CUNY doctoral student, Queens College adjunct professor, and a co-author of the study.
Stress hormones like cortisol help with the “fight or flight” survival response to a dangerous or stressful event by contributing to physical and mental speed. “But during pregnancy, such reactions may not be beneficial to the fetus,” Nomura said. “Cortisol can pass from the mother through the placenta on to the fetus, influencing gene expression, brain development and, ultimately, long-term behavioral outcomes. If the release of stress hormones is prolonged or of high magnitude, it can have sustainable effects on the developing baby.”
Pregnancy prepares the fetus for life outside the womb. “But mismatched preparation can occur if the child is set up to respond to acutely stressful natural disasters that seldom occur after birth,” Nomura said. “This may make the child hypervigilant, anxious or otherwise ill-suited to regulate their emotions. If not ameliorated, these patterns may be passed on to further generations through epigenetic changes or learned behaviors.”
The researchers are now conducting a follow-up study on the children born to clinically depressed mothers who were pregnant during Sandy. The scientists still are analysing the data, but preliminary results indicate that, nearly seven years later, “the children are more fearful, tend to become ‘overloaded’ with stimuli—and overreact to it—and have a more difficult time recovering from daily life’s small stresses when compared to children whose mothers were not depressed nor exposed to Superstorm Sandy during pregnancy,” Nomura said.
Nomura’s team recommends monitoring for at-risk mothers during future extreme weather events, as the increasing number of natural catastrophes are likely to put more mothers and infants at risk for mental health problems. “We may need to invest resources in helping pregnant women be more resilient when they are exposed to climate change and other hardships beyond their control,” Nomura said.
The American College of Obstetrics and Gynecology issued screening guidelines for treating depression during pregnancy in response to a 2004 study that showed only one in three clinically depressed pregnant people was diagnosed with depression, and only one in six received appropriate treatment.
Nomura noted that a natural disaster — while serious — was only one of several compounding factors that can harm a pregnancy. “We have to learn to be kinder to women and family during their pregnancy,” Nomura said. “We need to bring awareness and lower the stigma associated with women experiencing depression at the time of childbirth. Our society deems this as a happy period in a woman’s lifetime, but it’s important to recognise and support women and children who struggle psychologically and physically during this period.”
This story was published with permission from Nexus Media.
Thanks for reading to the end of this story!
We would be grateful if you would consider joining as a member of The EB Circle. This helps to keep our stories and resources free for all, and it also supports independent journalism dedicated to sustainable development. For a small donation of S$60 a year, your help would make such a big difference.