In Los Angeles, Hispanic women who were exposed to air pollution and stress during pregnancy were more likely to give birth to babies with low birth weight, according to a new study published October 25 in the JAMA Network Open.

Exposures to such contaminants and psychological stress disrupted delicate and precisely programmed fetal growth processes during the beginning and middle of pregnancy, according to the study.

“In this cohort study of 628 predominately low-income Hispanic women who were pregnant, exposures to particulate matter and nitrogen dioxide in early pregnancy to mid pregnancy were significantly associated with lower birth weight, particularly for mothers experiencing higher perceived stress during the prenatal period and living in a neighborhood with a high level of stressors from environmental pollution”, describes the study’s finding.

“Although air pollution has a harmful effect on many different populations, our study identified the effects on expectant mothers who are already most vulnerable”, first author Zhongzheng (Jason) Niu, a postdoctoral scholar at the University of Southern California’s (USC) Keck School of Medicine, said in a statement published by The Hill.

Low birth weight is also connected to the long-term development of certain diseases, such as diabetes, heart disease, high blood pressure, intellectual disabilities, metabolic syndrome and obesity. 

While scientists were already aware that air pollution is linked to lower birth weight and future disease risks, Niu explained that “the addition of high perceived stress is another factor” that exacerbates these circumstances.

According to The Hill, “The researchers also assessed neighborhood-level stressors by using a statewide metric called CalEnviroScreen Score, which serves to pinpoint areas that have been disproportionately burdened by multiple sources of pollution”.

The average age of the patients was 28 years, with 73 percent self-identifying as Hispanic and 32 percent listing Spanish as their preferred language, according to the study. About 21 percent of the mothers reported high stress in their lives, while 60 percent lived in an area characterized by a disproportionately high pollution burden, the authors found.

“Despite reductions in air pollution in California, we are still seeing harmful effects of air pollutants on birth weight, a key indicator of baby’s future health, in vulnerable populations”, said senior author Carrie Breton, a professor at the Keck School of Medicine in a statement released by The Hill.

The study confirms the importance of considering a combination of stressors and pollutants in promoting healthy fetal growth. In addition, the continuous monitoring of air pollutants needs to be a priority, as well as the reduction of stressors that directly affect individuals, demanding urgent public policies in these communities to mitigate these factors.