Maternal exposure to air pollution and psychological stress can disrupt fetal growth

Maternal exposure to air pollution and psychological stress can disrupt fetal growth

Fetal Growth -; that is delicately and precisely programmed -; may be disrupted by a mother's exposure to air pollution and psychological stress during early to mid-pregnancy, a new USC study shows.

The findings, published today in JAMA Network Open, suggest that protecting pregnant women from air pollution may improve birth weight, particularly in stressed mothers living in polluted areas.

Although air pollution has a harmful effect on many different populations, our study identified the impact on expectant mothers, who are already most vulnerable. The addition of high perceived stress is another factor contributing to this problem. We already know that air pollution is linked to low birth weight and future disease risk. Protecting pregnant women from these risks would ultimately protect future generations.”

Zhongzheng (Jason) Niu, postdoctoral fellow and research associate, Keck School of Medicine of USC, and first author of the study

Low birth weight newborns are at increased risk of neonatal mortality and potential complications such as breathing problems, brain hemorrhages, jaundice and infections. Low birth weight is also associated with long-term disease risks, including Diabetes, heart disease, high blood pressure, intellectual and developmental disabilities, metabolic syndrome and obesity.

Identify mothers at risk

Between 2015 and 2021, USC's Maternal and Developmental Risks from Environmental and Social Stressors (MADRES) center collected data from 628 predominantly low-income Hispanic women pregnant with a single child.

Patients were recruited primarily from Eisner Health in downtown Los Angeles and the LAC + USC prenatal clinic. Biospecimen data, medical records, and residence information were collected during clinic visits. Participants completed a Perceived Stress Scale questionnaire to assess their perceptions of stress. Their neighborhood-level stressor was measured using the CalEnviroScreen Score, a California screening tool to identify neighborhoods disproportionately burdened by multiple sources of pollution and population vulnerability.

The average age of the participants was 28 years; 73% described themselves as Spanish and 32% listed Spanish as their preferred language. Twenty-one percent of mothers reported high levels of stress in their lives. More than 60% of participants lived in a neighborhood with a CalEnviroScreen score greater than 50, indicating high cumulative exposure.

Microscopic particles threaten the development of babies

Three components of polluted air were examined: PM2.5, PM10 and NO2. Pollutant levels were monitored using air quality data (U.S. Environmental Protection Agency Air Quality System) with an average of four monitoring stations within 5 to 9 miles of each participant's home address.

Emissions from the combustion of gasoline, oil, diesel fuel, or wood produce PM2.5 particles 2.5 micrometers or less in diameter -; 30 times smaller than a strand of hair. PM10 is less than 10 micrometers in diameter and is found in dust and smoke.

Nitrogen dioxide, or NO2, is another pollutant released when fossil fuels are burned at high temperatures.

Daily estimates of 24-hour average NO2 and particulate matter were assigned to each participant's place of residence, from 12 weeks before conception to 36 weeks of pregnancy.

Conclusions

Exposure to particulate matter and nitrogen dioxide in early to mid-pregnancy is significantly associated with lower birth weight, researchers found. On average, birth weight was 9.5 grams lower for each interquartile increase (4 µg/m3) in PM2.5 exposure during weeks 14 to 22 of pregnancy.

Even more worrying, mothers with high levels of stress, who also live in the most environmentally polluted areas, experienced greater declines in birth weight. In this group, mothers exposed to the highest levels of PM2.5 during the fourth to 20th week of pregnancy gave birth to babies weighing 34 grams, or 1 ounce, less, and mothers exposed to the highest levels of PM10 during the ninth to 14th week of pregnancy gave birth to babies weighing 39.4 grams less, on average.

In the same group, exposure to NO2 from ninth to 14 weeks of pregnancy was associated with a 40.4 gram decrease in birth weight. Exposure at 33 to 36 weeks of pregnancy showed the largest decrease in birth weight: 117.6 grams, or 4.1 ounces.

“Despite reductions in air pollution in California, we are still seeing harmful effects of air pollutants on birth weight, a key indicator of the future health of babies, in vulnerable populations,” said last author Carrie Breton, professor of population and health sciences at the Keck School of Medicine. "The women most at risk are those who are affected by multiple types of stressors and experience stress in different ways. The combination of stressors and pollutants is important to protect the health of babies. Further monitoring of air pollutants must remain a priority. Reducing individual and neighborhood stressors should also be a priority, particularly at the policy level."

Source:

University of Southern California

Reference:

Niu, Z., et al. (2022) Association between ambient air pollution and birth weight through maternal stressors at the individual and neighborhood levels. JAMA network opened. doi.org/10.1001/jamanetworkopen.2022.38174.

.