The relationship between air pollutants and maternal socioeconomic factors on preterm birth in California urban counties

Abstract

Background Preterm birth is the leading cause of perinatal morbidity and mortality in the U.S. and disparities among racial and ethnic groups persist. While etiologies of preterm birth have not been fully elucidated, it is probable that environmental and social factors play a role. Objective We hypothesized that there is an interactive association between exposure to fine particulate matter (PM2.5) or ozone (O3) and neighborhood socioeconomic factors that increase the risk of preterm birth. Methods We conducted a retrospective study using geocoded birth certificate data between 2007 and 2011, daily ambient air quality data on PM2.5 and O3, and American Community Survey (2007–2011 5-year estimates) data to assess census tract-level socioeconomic factors in California urban counties. Results Our study found a small positive association between maternal exposures to PM2.5 and O3 and preterm birth that varied by gestational exposure period. In mixed-effects models, we found an increase in the risk of preterm birth for a one-unit change in PM2.5 averaged across the entire pregnancy (AOR = 1.02, 95% CI: 1.01, 1.02) and O3 during 3-months pre-pregnancy (AOR = 1.03, 95% CI: 1.02, 1.04). Interaction between census tract-level factors and air pollutants showed an increase in the risk of preterm birth among mothers living in higher socioeconomic areas, though, a fixed cohort bias sensitivity analysis showed these associations were not significant. Significance These findings substantiate previous studies that showed associations between air pollution and preterm birth, even as pollution levels have decreased. This study has important implications for policy decisions and may help inform research on potential mechanisms of preterm birth.

Association between Maternal Exposure to Ambient Air Pollution and the Risk of Preterm Birth: A Birth Cohort Study in Chongqing, China, 2015–2020

“…The past decade has witnessed mounting attention on researching the association between maternal exposure to air pollutants and adverse birth outcomes. Many studies have demonstrated positive associations between ambient air pollution exposure and PTB [ 23 , 24 , 25 , 26 ], especially for PM 2.5 and PM 10 . Lei Yuan and Ying Tian (2019) reviewed 42 studies on the association between maternal exposure to PM 2.5 and PTB; among 18 studies selected, prenatal PM 2.5 exposure has strong effects on PTB [ 27 ].…”

A Review of Racial Disparities in Infant Mortality in the US

“…Predominantly Black neighborhoods are also characterized as having higher allergen counts as well as pollution levels of almost 1.54 times higher than the overall population [ 73 ]. Multiple studies have indicated that pollution can increase the risk of preterm births and lead to the development of unfavorable health conditions such as diabetes [ 74 , 75 ]. The susceptibility of Black mothers to having preterm births is likely contributed to by their tendency to reside in relatively unfavorable environments.…”

Associations between combined exposure to environmental hazards and social stressors at the neighborhood level and individual perinatal outcomes in the ECHO-wide cohort

“…Examining these combined exposures is important for understanding how total neighborhood contexts can impact early life outcomes. Studies on the potential for neighborhood-level socioeconomic status to modify the relationship between air pollutants and birth outcomes suggest the interactions between neighborhood factors may be synergistic (Généreux et al, 2008;Mekonnen et al, 2021;Padula et al, 2014;Ponce et al, 2005;Yi et al, 2010). These studies investigated relationships between SES and single environmental exposures.…”

“…These studies investigated relationships between SES and single environmental exposures. For example, Généreux et al, 2008 included distance to roadways as the exposure of interest, Padula et al (2014) included ambient carbon monoxide, nitrogen dioxide, and particulate matter, and Mekonnen et al (2021) included particulate matter and ozone. A review of interactions between social determinants and environmental exposures on perinatal and childhood health outcomes found that 28 of the 39 (72%) review studies reported synergistic associations between social and environmental factors (Appleton et al, 2016).…”