Impact of road traffic pollution on pre-eclampsia and pregnancy-induced hypertensive disorders

BACKGROUND: Road traffic is a majorsource of air pollution and noise. Both exposures have been associated with hypertension in adults, but pregnant womenhave been less studied.METHODS: We examined single and joint effects of ambient air pollution and road traffic noise on preeclampsia and pregnancy-induced hypertensive disorders among 72,745 singleton pregnancies (1997-2002) from the Danish National Birth Cohort with complete covariate data and residential address history from conception until liveborn birth. Nitrogen dioxide (NO2) and noise from road traffic (Lden) weremodeled at all addresses. Outcome and covariate data were derived from registries, hospital records, and questionnaires.RESULTS: A 10-µg/m increase in NO2 exposure during first trimester was associated with increased risk of preeclampsia (n=1,880, adjusted odds ratio = 1.07 [95% confidence interval = 1.01 to 1.14]) and pregnancy-induced hypertensive disorders (n=2,430, 1.07 [1.01 to 1.13]). A 10-dBhigher road traffic noise was also associated with increased risk of preeclampsia (1.10 [1.02 to 1.18]) and pregnancy-induced hypertensive disorders (1.08 [1.02 to 1.15]). For both exposures the associations were strongest for mild preeclampsia (n=1,393) and early-onset preeclampsia (n=671) while higher risk for severe preeclampsia(n=487) was not evident. In mutually adjusted models estimates for both exposures decreased and only the association between NO2 and mild preeclampsia remained.CONCLUSIONS: Road traffic may increase the risk of preeclampsia and hypertensive disorders in pregnancy through exposure to both ambient air pollution and noise, although associations with the two exposures were generally not found to be independent of one another. See video abstract, http://links.lww.com/EDE/B112