Ambient carbon monoxide and fine particulate matter in relation to preeclampsia and preterm delivery in western Washington State.
BACKGROUND
Preterm delivery and preeclampsia are common adverse pregnancy outcomes that have been inconsistently associated with ambient air pollutant exposures.


OBJECTIVE
We aimed to prospectively examine relations between exposures to ambient carbon monoxide (CO) and fine particulate matter [≤ 2.5 μm in aerodynamic diameter (PM2.5)] and risks of preeclampsia and preterm delivery.


METHODS
We used data from 3,509 western Washington women who delivered infants between 1996 and 2006. We predicted ambient CO and PM2.5 exposures using regression models based on regional air pollutant monitoring data. Models contained predictor terms for year, month, weather, and land use characteristics. We evaluated several exposure windows, including prepregnancy, early pregnancy, the first two trimesters, the last month, and the last 3 months of pregnancy. Outcomes were identified using abstracted maternal medical record data. Covariate information was obtained from maternal interviews.


RESULTS
Predicted periconceptional CO exposure was significantly associated with preeclampsia after adjustment for maternal characteristics and season of conception [adjusted odds ratio (OR) per 0.1 ppm=1.07; 95% confidence interval (CI), 1.02-1.13]. However, further adjustment for year of conception essentially nullified the association (adjusted OR=0.98; 95% CI, 0.91-1.06). Associations between PM2.5 and preeclampsia were nonsignificant and weaker than associations estimated for CO, and neither air pollutant was strongly associated with preterm delivery. Patterns were similar across all exposure windows.


CONCLUSIONS
Because both CO concentrations and preeclampsia incidence declined during the study period, secular changes in another preeclampsia risk factor may explain the association observed here. We saw little evidence of other associations with preeclampsia or preterm delivery in this setting.
Department of Social and Preventive Medicine, School of Public Health and Health Professions, State University of New York, Buffalo, New York 14214-8001, USA. cbrudra@buffalo.edu
Carole B
CB
Rudra
Michelle A
MA
Williams
Lianne
L
Sheppard
Jane Q
JQ
Koenig
Melissa A
MA
Schiff
D000328:Adult; D000393:Air Pollutants / Q000009:adverse effects* / Q000032:analysis; D002248:Carbon Monoxide / Q000009:adverse effects* / Q000032:analysis; D015331:Cohort Studies; D005260:Female; D006801:Humans; D018811:Maternal Exposure; D052638:Particulate Matter / Q000009:adverse effects* / Q000032:analysis; D011225:Pre-Eclampsia / Q000139:chemically induced / Q000453:epidemiology / Q000209:etiology*; D011247:Pregnancy; D047928:Premature Birth / Q000139:chemically induced / Q000453:epidemiology / Q000209:etiology*; D011446:Prospective Studies; D012307:Risk Factors; D011795:Surveys and Questionnaires; D014861:Washington / Q000453:epidemiology; D055815:Young Adult
D000393:Air Pollutants; D052638:Particulate Matter; D002248:Carbon Monoxide
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