Table 1.
Characteristics of primary studies.
| Reference | Pollutant | Outcome | Design | Location | Time period | Sample size | Exposure period | Exposure type | Covariates |
|---|---|---|---|---|---|---|---|---|---|
| Dadvand et al. 2013 | NOx, NO2, PM10, PM2.5, PM2.5-10 | Preeclampsia | Hospital-based Cohort | Barcelona, Spain | 01-Mar-2000- 30-Jun-2005 | 8,398 | Trimester, entire pregnancy | Continuous | Age, parity, race, smoking, BMI, alcohol consumption, season, year, SES, education, marital, diabetes |
| Lee et al. 2013 | PM10, PM2.5, O3 | GHT Preeclampsia | Hospital-based Cohort | Philadelphia, USA | 01-Jan-1997-31-Dec-2002 | 34,705 | First trimester | Continuous | Age, parity, race, smoking, season of birth, year of conception |
| Mobasher et al. 2013 | NO2, O3, CO, PM2.5, PM10 | HDP | Case-control | California and Nevada, USA | 01-Jan-1996-31-Dec-2008 | 298 | Trimester | Continuous | Age, parity, smoking, ETS, year of conception |
| Olsson et al. 2013 | NOx, O3 | HDP | Register-based Cohort | Greater Stockholm area, Sweden | 01-Jan-1998-31-Dec-2006 | 120,755 | First trimester | Continuous | Age, parity, education, area of origin, maternal asthma, season of conception, conception year |
| Pereira et al. 2013 | NO2 | Preeclampsia | Register-based Cohort | Perth, Australia | 01-Jan-2000-31-Dec-2006 | 23,452 | Trimester, entire pregnancy | Continuous | Age, parity, diabetes, aboriginal status, season of conception, smoking, socioeconomic index for areas score |
| van den Hooven et al. 2011 | NO2, PM10 | GHT Preeclampsia | Prospective Cohort | Rotterdam, Netherlands | 01-Jan-2001-31-Dec-2005 | 7,006 | Entire pregnancy | Continuous | Age, parity, race, education, height, weight, folic acid supplementation, smoking, alcohol consumption, noise exposure |
| Vinikoor-Imler et al. 2012 | PM10, PM2.5 | HDP | Register-based Cohort | North Carolina, USA | 01-Jan-2000-31-Dec-2003 | 222,775 | Entire pregnancy | Continuous | Age, parity, education, smoking, race, marital status, neighborhood deprivation index |
| Wu et al. 2011 | CO, NO, NO2, NOx, PM2.5, PM10 | Preeclampsia | Hospital-based Cohort | California, USA | 01-Jan-1997-31-Dec-2006 | 81,186 | Trimester, entire pregnancy | Continuous | Age, parity, race, prenatal care insurance type, poverty, season of conception, diabetes |
| Xu et al. 2013 | CO, NO2, SO2, O3, PM2.5, PM10 | HDP | Register-based Cohort | Florida, USA | 01-Jan-2004-31-Dec-2005 | 22,041 | Trimester, entire pregnancy | Continuous | Age, parity, race, education, marital, smoking, season, year, prenatal care, median household income |
| Zhai et al. 2012 | CO | Preeclampsia | Register-based Cohort | Ontario, Canada | 01-Jan-2004-31-Dec-2009 | 127,370 | Entire pregnancy | Quartiles, Continuous | Age, parity, smoking, previous cesarean section delivery, maternal health problem (chronic hypertension, diabetes, heart disease), income, education |
Abbreviations: NO-nitrogen monoxide, NO2-nitrogen dioxide, NOx-nitrogen oxide, SO2-sulfur dioxide, O3-ozone, CO-carbon monoxide, PM2.5-particulate matter of median diameter<2.5μm, PM2.5-10-particulate matter of median diameter between 2.5μm and 10μm, PM10-particulate matter of median diameter<10μm, GHT-gestational hypertension, HDP-hypertensive disorder of pregnancy, BMI-body mass index, SES-socioeconomic status, ETS-environment tobacco smoking.