A recent study shows a 1 percent increase in postpartum depression risk with every 1-degree temperature increase.
Women who have recently given birth and are exposed to heat and fluctuating ambient temperatures face a significantly higher risk of developing postpartum depression (PPD), according to a recent study.
The research, which involved nearly 430,000 women, found that for every temperature increase of around 1 degree Celsius, PPD risk also increased by 1 percent. Environmental factors like air pollution and low air conditioning usage also exacerbated PPD risk.
“Temperature-associated PPD risks were significantly higher among mothers with more severe exposure” to air pollutants, the authors wrote.
Jun Wu, senior author of the study and professor of environmental and occupational health at the University of California–Irvine Program in Public Health, told The Epoch Times that the study’s findings could help guide ways to prevent postpartum depression.
Understanding Postpartum Depression Risk Factors
PPD is a form of depression that occurs within four weeks to a year after childbirth. It is characterized by symptoms such as persistent sadness, loss of interest in activities, and difficulty bonding with the baby.
Overweight or obese women and those who have had Cesarean or preterm birth, medical complications, and have given birth to multiple children are at greater risk of PPD.
The link was stronger for hotter times of the day than cooler times.
The study did not provide an ideal temperature for postpartum women.
“Even in Southern California, where people might assume residents are accustomed to warm temperatures, we still observed a positive association between temperature exposure and postpartum depression risk,” Wu said. “I imagine that an increase in temperature could have a stronger impact on someone living in a colder climate zone, where high temperatures are less common.”
Both recent and prolonged exposure had similar effects on PPD risk.
Areas with fewer homes equipped with air conditioning showed a stronger correlation between significant daily temperature fluctuations and PPD incidence.
Also, mothers aged 25 or older, along with those from African American, Asian, or Hispanic communities, were found to be at higher risk.
“Many recent studies underscore the urgent need to combat climate change, as its effects extend beyond environmental degradation and directly impact human health, even harming unborn babies,” Aidan Charron, associate director of Global Earth Day, an organization whose mission is to “diversify, educate and activate the environmental movement worldwide,” told The Epoch Times.
Prenatal and Postpartum Vulnerabilities
High ambient temperatures have long been linked to mental health challenges. Rising temperatures can exacerbate daily stresses and activate physiological responses that adversely affect mental health.
Women are more vulnerable to temperature changes during pregnancy and the postpartum period. Biological and hormonal changes affect a pregnant woman’s ability to regulate her core body temperature. This makes her more susceptible to extreme temperatures.
The hypothalamic-pituitary-adrenal (HPA) axis, which regulates the body’s stress response, becomes more active in higher temperatures. It releases cortisol, a stress hormone that causes inflammation. The HPA axis can get overwhelmed when environmental temperatures surpass the body’s core temperature, causing a strong stress response.
Heat stress also compromises the blood-brain barrier (BBB), a protective shield that normally prevents harmful toxins from entering the brain. When the BBB becomes more permeable due to heat exposure, these harmful substances infiltrate the brain, disrupting the HPA axis and weakening the body’s ability to regulate stress.
Amplifying Effect of Environmental Factors
In addition to exposure to high temperatures, the study also found that air pollution, limited outdoor green space, and low rates of air conditioning usage worsened the risk of high temperatures on PPD risk. “Raising ambient temperature may stimulate a greater exposure to hazardous air pollutants,” such as through increased sweating, blood flow, and breathing, the authors wrote.
Wu offered some assumptions about how these factors modify the association between PPD and high temperatures. She noted that more green space could mitigate the effects of high temperatures, as people in these areas may also face high air pollution exposure.
“Air pollution by itself can have adverse impacts on mental health outcomes,” she said, pointing to the harmful effects of particulate matter entering the body and brain.