Preterm birth after the Utah Valley Steel Mill closure: a natural experiment.
BACKGROUND
: Prior studies have linked the Utah Valley Steel Mill closure that took place between August 1986 and September 1987 to improvements in several health outcomes. So-called natural experiments ease concerns over confounding and exposure misclassification, concerns that are common in studies of air pollution and pregnancy outcome.


METHODS
: We compare birth outcomes for Utah mothers within and outside the Utah Valley, before, during, and after the mill closure.


RESULTS
: Mothers who were pregnant around the time of the closure of the mill were less likely to deliver prematurely than mothers who were pregnant before or after; effects were strongest for exposure during the second trimester. Preterm birth within the Utah Valley did not change during the time of mill closure. No patterns for birth weight were observed.


CONCLUSIONS
: These results support other studies that have found effects on preterm birth of air pollution exposure early in pregnancy.
Parker
Jennifer D
JD
Office of Analysis and Epidemiology, National Center for Health Statistics, Centers for Disease Control and Prevention, Hyattsville, MD 20782, USA. jdparker@cdc.gov
Mendola
Pauline
P
Woodruff
Tracey J
TJ
D000397:Air Pollution / Q000009:adverse effects*; D001719:Birth Certificates; D016022:Case-Control Studies; D004784:Environmental Monitoring; D062665:Epidemiological Monitoring; D005260:Female; D006801:Humans; D008669:Metallurgy; D011247:Pregnancy; D047928:Premature Birth / Q000453:epidemiology / Q000209:etiology*; D012189:Retrospective Studies; D013232:Steel; D014589:Utah / Q000453:epidemiology; D044465:White People
D013232:Steel