Exposure to Ambient Air Pollutant PM in the Second Trimester of Pregnancy Is Associated with Preterm Birth: A Birth-Based Health Information Cohort Study.

OBJECTIVES

We evaluated the effects of exposure to high concentrations of particulate matter (PM) on preterm birth (PTB) and identified a critical concentration of PM that could lead to PTB a birth-based health information cohort study.

METHODS

We conducted a birth-based cohort study consisting of nonanomalous singleton births at 22-42 weeks. PTB was defined as babies born alive before 37 weeks of pregnancy. Pregnancy period exposure averages were estimated for PM based on the China National Environmental Monitoring Centre (CNEMC). Pregnant women who lived within 50 km of the monitor station were recruited into this study. Logistic regression analyses were performed to determine the association between PTB and exposure to PM at different pregnancy periods with adjustment for confounding factors.

RESULTS

The relative frequency of PTB was 8.7% in the study cohort of 5,291 singleton live births. A total of 1137 women had a high level of PM exposure (≥60 g/m) in the second trimester of pregnancy. The average concentrations of PM in the first, second, and third trimesters of pregnancy and throughout pregnancy were 53.8 g/m, 54.2 g/m, 55.6 g/m, and 54.3 g/m, respectively. The generalized additive model (GAM) analysis showed that there was a nonlinear correlation between PM and PTB in the second trimester of pregnancy ( < 0.001). The adjusted odds ratio between PTB and low concentration PM exposure (PM < 60 g/m) in the second trimester of pregnancy was 1.01 (95% CI 0.95-1.05). However, high PM exposure (PM ≥ 60 g/m) in the second trimester of pregnancy had an increased PTB risk even after adjustment for coexisting risk factors with an adjusted odds ratio of 1.78 (95% CI 1.69-1.87), and the incidence of PTB increased with an increase in PM exposure.

CONCLUSIONS

Our research discovered that exposure to high levels of PM increases the risk of PTB and the second trimester is the most vulnerable gestational period to ambient air pollution exposure. PM concentrations more than 60 g/m are detrimental to pregnant women in their second trimester. This study has implications for health informatics-oriented healthcare decision support systems.