Association between fine particulate matter (PM2.5) and infant mortality in a North Carolina Birth Cohort (2003-2015)
On this page:
Background: Many studies have quantified the association between fine particulate matter (PM2.5) and adult mortality. Several studies have evaluated coarse particulate matter (PM10) and postneonatal mortality, but there are relatively few studies about PM2.5 and infant mortality. We investigated the association between long-term PM2.5 exposure and infant and postneonatal mortality.
Methods: We conducted an unmatched case-control study of infant mortality sampling 10 controls per case from a North Carolina birth cohort (2003-2015). PM2.5 exposure was estimated at the birthing parent’s residence based on spatiotemporal modeling of PM2.5 concentrations at the census block averaged over 2-week periods. We performed logistic regression and calculated odds ratios (ORs) and 95% confidence intervals (CIs) for an increase equal to the interquartile range of PM2.5 (4.0 µg/m3) for five critical exposure periods (trimesters, pregnancy, and first month alive). Due to the decrease in PM2.5 concentrations over the study period, we conducted stratified analyses for two time periods: 2003-2009 and 2011-2015.
Results: Our analytical dataset included 1,315,691 infants from which we identified 5,992 cases of infant mortality and sampled 60,000 non-cases to serve as controls. After adjusting for covariates, the odds of infant mortality increased by 4% (OR: 1.04, 95% CI: 0.95, 1.14) for each 4.0 µg/m3 increase in PM2.5 exposure averaged over the entire pregnancy for 2003-2009, while the odds of infant mortality decreased by 15% (OR 0.85, 95% CI: 0.72, 1.01) for 2011-2015. We observed similar patterns for postneonatal mortality and with trimester specific exposures.
Conclusions: Our results suggest that long-term PM2.5 exposure over the entire pregnancy is modestly associated with infant and postneonatal mortality during the study period when PM2.5 concentrations were higher (i.e., mean > 12 µg/m3). We observed generally null or negative effect estimates during the study period when PM2.5 concentrations were lower (i.e, mean < 9 µg/m3). [s1] Future work investigating the shape of the concentration-response relationship will be important to inform policies that protect infant’s environmental health.
[s1]I looked at >12 and the estimates are high but I don’t present this figure at the moment. Okay for abstract but might want to consider with the paper.