Air pollution in the week prior to delivery and preterm birth in 24 Canadian cities: a time to event analysis.

ABSTRACT:

Background

Numerous studies have examined the association between air pollution and preterm birth (< 37 weeks gestation) but findings have been inconsistent. These associations may be more difficult to detect than associations with other adverse birth outcomes because of the different duration of exposure in preterm vs. term births, and the existence of seasonal cycles in incidence of preterm birth.

Methods

We analyzed data pertaining to 1,001,700 singleton births occurring between 1999 and 2008 in 24 Canadian cities where daily air pollution data were available from government monitoring sites. In the first stage, data were analyzed in each city employing Cox proportional hazards models using gestational age in days as the time scale, obtaining city-specific hazard ratios (

SUBMITTER: Stieb DM 

PROVIDER: S-EPMC6318965 | biostudies-literature | 2019 Jan

REPOSITORIES: biostudies-literature