Stress on pregnant people and exposure to pollution impacts babies’ size and health, USC study shows

Research has shown that air pollution hurts babies before birth, but the impact could be worse on children of low-income and highly stressed mothers, a new USC study has found.

The study, published last week, found that mothers suffering from stress for personal reasons or because of where they live had babies born with lower weights.

The researchers, focusing on low-income Hispanic women in Los Angeles, began work in 2015 in what Zhongzheng “Jason” Niu, the study’s first author, called a “big effort.”

It included 628 women pregnant with a single child, 21% of whom reported experiencing high stress levels.

During the data collection process, the participants were asked to fill in a questionnaire to understand stressors and their ability to cope with them.

“Some people may have a higher resilience or they have better support,” said Niu, a postdoctoral scholar and research associate at the USC Keck School of Medicine. “So even though the stressful event is the same, people have different reactions to that.”

The researchers used the CalEnviroScreen Score to identify disproportionately burdened California communities. The website allows users to see places in California experiencing cumulative burdens of environmental pollution and socioeconomic factors that might increase susceptibility to the effects of pollution.

The overall CalEnviroScreen score is calculated by multiplying the pollution burden and population characteristics scores. More than half of the participants in the research study lived in areas with a score greater than 50 out of 100. The greater the score, the greater the burden.

Babies exposed to air pollution in the womb have their lung development affected, or they can be born too early or too small. Low birth weight and premature birth are leading risk factors for death in the first month of life. They are also related to higher mortality rates in people. Such kids are more vulnerable to problems like lower-respiratory infections, diarrheal diseases, brain damage and inflammation, blood disorders and jaundice.

The study focused on three air pollutants: nitrogen dioxide (released from the burning of fossil fuels), fine particulate matter PM2.5 (from the combustion of gasoline, oil, diesel fuel or wood produce) and PM10 (dust from construction sites, industrial sources or wind-blown from open lands), and found strong relations between exposure to these pollutants and lower birth weight.

According to Rupa Basu, chief of the air and climate epidemiology section at the California Office of Environmental Health Hazard Assessment, it’s important to include environmental racism when talking about environmental pollution. “So there are some differences by the exposure [of PM2.5]. So if you look at areas that generally have more Black, Latino and also Asian populations, they tend to have generally higher levels of PM2.5 and other exposures. And it’s because places where people live are closer to freeways, closer to fossil fuel combustion areas, and I think there’s also less resources going into those areas to decrease the emissions.”

L.A. is one of many cities in California with the most polluted air in the country, according to an American Lung Association analysis this year, a national report card on air quality throughout the nation.

“The biggest issues are systemic regulatory failure, systemic disinvestment, the lack of political power and political will to change the oppressive systems that are continuing to allow industry to sit next to communities [and] to continue to pollute…and not really address the problem from a root cause,” said Paula Torrado Plazas, manager of the health and environment program at Physicians for Social Responsibility-L.A.

What’s unique about the USC study is that it uses models that focus on the sensitive time periods of exposure, which is early to mid-pregnancy, when the organs in the baby are forming.

For mothers with heightened levels of stress or those who live in neighborhoods with high levels of pollution and scarce health care resources, the study found wider critical periods in pregnancy and more changes in the babies.

“There is no safe level of air pollution,” emphasized Niu.

According to Basu, newer studies are showing the connection between mental health and exposure to pollution. Smaller pollutants could pass the brain blood barrier and cause cognitive impairment, for example, neurological developmental disorders in infants and children.

Niu explained studies have shown that exposure of women to air pollution could have a direct effect on the placenta, which in turn may be unable to provide enough nutrients for the baby to grow. Add to that the psychological stress, and the regulatory system in the women’s body gets impacted, hurting the baby.

“From a public health point of view, it’s important to realize that fetuses, infants, pregnant women, they’re the most vulnerable of all populations,” Basu said. “So if you’re seeing effects in these populations, then it is…a huge environmental stressor.”

Plazas said that addressing stressors, cumulative impacts and investing in community driven mental health solutions needs a big picture perspective. One community health center, she said, isn’t enough.

“There’s not even close to what communities need.” Plazas said. “I think there need to be stronger political champions and justice champions that are bringing resources to the communities and are allocating funds in a way that is equitable and not continuing to fuel fossil fuel dependency, but are actually attributing to the solutions that communities are advocating for.”

This story has been updated to correctly quote a source, as well as to correctly name Physicians for Social Responsibility-L.A. Annenberg Media regrets this error.