Sources Of Fine Particulate Matter And Risk Of Preterm Birth In Connecticut 2000-2006: A Longitudinal Study

Pereira, Gavin

INTRODUCTION: Previous studies have examined the effects of fine particulate matter (PM_2.5) on risk of preterm birth but there is a dearth of longitudinal studies on this topic and a paucity of studies that have investigated specific sources of this exposure. The objective of this study was to identify sources of fine particulate matter in Connecticut and assess whether anthropogenic sources are associated with risk of preterm birth, comparing successive pregnancies to the same woman.

METHODS: Birth certificates were used to select women who had vaginal singleton live-births at least twice in Connecticut 2000-2006 (N=23,123 women, N=48,208 births). We procured 4085 daily samples of PM_2.5 on Teflon filters from the EPA for six cities in Connecticut. Filters were analyzed for chemical composition, and Positive Matrix Factorization was used to determine contributions from PM_2.5 sources. Conditional logistic regression was applied, matching pregnancies to the same women, to calculate risk estimates for PM_2.5 sources and preterm birth.

RESULTS: Odds ratios of preterm birth per inter-quartile range increase in whole pregnancy exposure to dust, motor vehicle emissions, oil combustion and regional sulfur PM_2.5 sources were 1.01 (0.93, 1.09), 1.01 (0.92, 1.10), 1.00 (0.89, 1.12) and 1.09 (0.97, 1.22), respectively.

CONCLUSIONS: This was the first study to investigate the effects of sources of PM_2.5 on preterm birth and the first study to make use of longitudinal comparisons (matching on the mother) to better address individual-level confounding potentially inherent in all past studies. There was insufficient evidence to suggest that sources were statistically significantly associated with risk of preterm birth in Connecticut. However, elevated central estimates and previously observed adverse associations with mass concentration motivate the need for further research, which would benefit from study settings with high source exposures and longitudinal study designs, such as that adopted in this study.