The relationship between air pollution and low birth weight: effects by mother’s age, infant sex, co-pollutants, and pre-term births

Abstract

Previously we identified associations between the mother’s air pollution exposure and birth weight for births in Connecticut and Massachusetts from 1999–2002. Other studies also found effects, though results are inconsistent. We explored potential uncertainties in earlier work and further explored associations between air pollution and birth weight for PM10, PM2.5, CO, NO2, and SO2. Specifically we investigated: (1) whether infants of younger (≤24 years) and older (≥40 years) mothers are particularly susceptible to air pollution’s effects on birth weight; (2) whether the relationship between air pollution and birth weight differed by infant sex; (3) confounding by co-pollutants and differences in pollutants’ measurement frequencies; and (4) whether observed associations were influenced by inclusion of pre-term births. Findings did not indicate higher susceptibility to the relationship between air pollution and birth weight based on the mother’s age or the infant’s sex. Results were robust to exclusion of pre-term infants and co-pollutant adjustment, although sample size decreased for some pollutant pairs. These findings provide additional evidence for the relationship between air pollution and birth weight, and do not identify susceptible sub-populations based on infant sex or mother’s age. We conclude with discussion of key challenges in research on air pollution and pregnancy outcomes.

Associations between prenatal traffic-related air pollution exposure and birth weight: Modification by sex and maternal pre-pregnancy body mass index

“…Their re-analyses of data from a case-control study in California (Wilhelm and Ritz 2003) also found significant associations between nitrogen dioxide (NO 2 ) estimated by distance-weighted traffic density measures and low birth weight (<2,500 g) only among boys; on the other hand, sex-stratified analyses of PM 10 , carbon monoxide (CO), and ozone did not show significant association in either sex (Ghosh et al 2007). Another study by Bell and colleagues (Bell et al 2008) also did not find significant sex differences. In another recent European multi-center study, Pedersen et al (Pedersen et al 2013) reported that the association between prenatal PM 2.5 and low birth weight was stronger for boys than girls, but the differences were not statistically significant.…”

“…Some studies demonstrate that male infants were at a higher risk of low birth weight in relationship to higher levels of air pollution compared with females (Ghosh et al 2007; Jedrychowski et al 2009), while others did not find statistically significant differences across sex (Bell et al 2008; Pedersen et al 2013). To our knowledge, only one study has examined effect modification by maternal obesity and found that maternal pre-pregnancy obesity significantly exacerbated the risk of polycyclic aromatic hydrocarbon (PAH) exposure on low birth weight in African-American newborns in a low income inner-city population (Choi and Perera 2012).…”

Characterizing the burden of disease of particulate matter for life cycle impact assessment

“…Also, the effect factor recommended here uses only dose-response information based on adults. The influence of PM inhalation on low birth weight (Bell et al 2008) and asthma among children and expressing this influence in terms of DALY also deserves further attention.…”

Prenatal Exposure to Fine Particulate Matter and Birth Weight

“…Previous studies have identified links between temperature and birth weight 25. Apparent temperature for the gestational period and each trimester for each study subject was calculated to represent overall response to temperature,26 and was used as a confounder in models, as applied in earlier work 5,6…”

“…Models adjusted for apparent temperature by trimester; infant’s sex; parity (first in birth order, not first in birth order); nature of delivery (vaginal, primary cesarean section, repeat cesarean section); trimester prenatal care began (first, second, or third trimester, no care, unknown); length of gestation in weeks; indicator variables for year of birth; and mother’s age (<20, 20–24, 25–29, 30–34, 35–39, >39 years), marital status (unmarried, married), education (<12, 12, 13–15, >15 years, or unknown), tobacco use during pregnancy (yes, no), alcohol use during pregnancy (yes, no), and race (white, African-American, other). Earlier research used similar approaches 3,5,6,8,18. Results are presented as the change in birth weight or risk of small-at-term birth per interquartile range (IQR) increase in exposure (source, constituent, or PM 2.5 ).…”