PURPOSE OF THE STUDY.
Prenatal exposures to maternal stress and physical toxins can affect children’s respiratory development and health. This study sought to examine the effects of prenatal psychosocial stressors (exposure to community violence [ECV]) and physical (traffic-related air pollution) stressors on childhood wheeze concurrently in an urban population.
The study enrolled 989 women (≥18 years old) in mid- to late pregnancy (28.4 ± 7.9 weeks) receiving care at Brigham & Women’s Hospital in Boston, Massachusetts, between August 2002 and December 2009. Of these, 708 mother–child pairs completed the study and were included in the analyses.
In this cohort study, mothers completed a multi-item survey to assess prenatal ECV, and results were summarized into a continuous scale. Prenatal exposure to black carbon was estimated based on residence during pregnancy by using land-use regression modeling; exposure to particulate matter of diameter <2.5 µm (PM2.5) was estimated by using land-use regression modeling incorporating satellite data. Mothers reported child wheeze at 3-month intervals up to age 24 months, with ≥2 episodes constituting repeated wheeze. The independent effects of ECV and air pollutants on repeated wheeze were analyzed by using multivariate logistic regression. Interactions between ECV and air pollutants were examined in stratified analyses.
Most mothers were of an ethnic minority (55% Hispanic and 29% black) and low socioeconomic status (62% with ≤12 years of education). Eighty-seven (12%) children wheezed repeatedly. In the multivariate models, ECV (odds ratio [OR]: 1.95 [95% confidence interval (CI): 1.13–3.36]) was independently associated with wheeze, adjusting for gender, race/ethnicity, maternal education, birth season, maternal atopy, and cockroach antigen. Black carbon (OR: 1.84 [95% CI: 1.08–3.12]) and PM2.5 (OR: 2.02 [95% CI: 1.20–3.40]) produced similar associations. In stratified analyses, a statistically significant association was shown between high prenatal ECV and increased repeated wheeze in the low black carbon and low PM2.5 groups, suggesting an interaction between ECV and air pollution.
The findings suggest that increased ECV and higher exposure to air pollutants in the prenatal period independently contribute to repeated wheeze in these urban children. In addition, the stratified analyses suggest that place-based psychosocial stressors may affect the mother such that physical pollutants adversely affect the fetus, even at relatively lower levels.
Childhood wheezing respiratory illness causes significant morbidity, particularly in urban communities of lower socioeconomic status, and characterizing its risk factors remains important. This study contributes to known associations with community violence and ambient pollution by providing additional evidence that they exert independent effects on wheeze and novel evidence that they may interact such that their effects are synergistic. Future larger scale studies are necessary to clarify these interactions, as well as to confirm that these relationships hold in the long term.
- Copyright © 2014 by the American Academy of Pediatrics