Table 2.
Summary of study characteristics for studies included in the meta-analysis
| Reference | Study location | Study design | Sample size | Pollutant(s) (exposure assessment method) | Exposure period | Overall ROB rating |
|---|---|---|---|---|---|---|
| (Basu et al. 2014) | California, USA (8 counties) | Cohort R | 646,296 | PM2.5 (Ambient monitoring) | Entire pregnancy, 1st, 2nd, and 3rd trimesters | Probably low |
| (Beland and Oloomi 2019) | southern USA | Cohort R | 9,324,839 | PM2.5 (Ambient monitoring) | Entire pregnancy | Probably low |
| (Bell et al. 2007) | Connecticut and Massachusetts, USA | Cohort R | 358,504 | PM2.5, PM10 (Ambient monitoring) | Entire pregnancy | Probably low |
| (Bell et al. 2010) | Connecticut and Massachusetts, USA (4 counties) | Cohort R | 76,788 | PM2.5 (Ambient monitoring) | Entire pregnancy, 1st, 2nd, and 3rd trimesters | Probably high |
| (Bijnens et al. 2016) | Flanders, Belgium | Cohort R | 4,760 | PM10 (Modeling) | Entire pregnancy, 1st, 2nd, and 3rd trimesters, last month, last week | Probably high |
| (Darrow et al. 2011) | Atlanta, USA (5 Counties) | Cohort R | 402, 627 | PM2.5, PM10, PM2.5–10 (Ambient monitoring) | Entire pregnancy, 3rd trimester only | Probably high |
| (Ebisu et al. 2016) | USA (224 Counties) | Cohort R | 8,017,865 | PM2.5–10 (Ambient monitoring) | Entire pregnancy, 1st, 2nd, and 3rd trimesters | Probably high |
| (Erickson et al. 2016) | British Columbia, Canada | Cohort R | 231,929 | PM2.5 (Modeling) | Entire pregnancy | Probably high |
| (Fong et al. 2019) | Massachusetts, USA | Cohort R | 907,766 | PM2.5 (Modeling) | Entire pregnancy | Probably low |
| (Geer et al. 2012) | Texas, USA | Cohort R | 1,548,904 | PM2.5, PM10 (Ambient monitoring) | Entire pregnancy | Probably low |
| (Giovannini et al. 2018) | Italy | Cohort R | 3,614 | PM10 (Ambient monitoring) | 1st, 2nd, and 3rd trimesters | High |
| (Gouveia et al. 2004) | São Paulo, Brazil | Cross-sectional | 179,460 | PM10 (Ambient monitoring) | Entire pregnancy, 1st, 2nd, and 3rd trimesters | Probably high |
| (Gray et al. 2010) | North Carolina, USA | Cohort R | 350,754 | PM2.5, PM10 (Ambient monitoring) | Entire pregnancy, 1st, 2nd, and 3rd trimesters | Probably low |
| (Gray et al. 2014) | North Carolina, USA | Cohort R | 457, 642 | PM2.5 (Modeling) | Entire pregnancy | Probably low |
| (Guo et al. 2020) | Guangdong province, China | Cohort R | 2,567,457 | PM2.5, PM10 (Ambient monitoring) | Entire pregnancy | Probably high |
| (Han et al. 2018) | Suzhou, China | Cohort R | 10,915 | PM2.5, PM10 (Ambient monitoring) | Entire pregnancy, 1st, 2nd, and 3rd trimesters | Probably high |
| (Hannam et al. 2014) | United Kingdom (Northwest England) | Cohort R | 203,562 | PM2.5, PM10 (Modeling) | Entire pregnancy, 1st, 2nd, and 3rd trimesters | Probably low |
| (He et al. 2018) | Zhengzhou, China | Cohort P | 591 | PM10 (Ambient monitoring) | Entire pregnancy, 1st, 2nd, and 3rd trimesters | Probably high |
| (Huang et al. 2015) | Beijing, China | Cohort R | 50,874 | PM10 (Ambient monitoring) | 1st, 2nd, and 3rd trimesters | Probably high |
| (Hyder et al. 2014) | Connecticut and Massachusetts, USA | Cohort R | 834,332 | PM2.5 (Ambient monitoring and modeling) | Entire pregnancy, 1st, 2nd, and 3rd trimesters | Probably low |
| (Jedrychowski et al. 2009) | Krakow, Poland | Cohort P | 481 | PM2.5 (Personal monitoring) | Entire pregnancy | Low |
| (Keller et al. 2017) | Georgia, USA | Cohort R | 403,881 | PM2.5 (Modeling) | 1st, 2nd, and 3rd trimesters | Probably low |
| (Kim et al. 2007) | Seoul, Korea | Cohort P | 1,514 | PM10 (Ambient monitoring) | 1st, 2nd, and 3rd trimesters | Probably low |
| (Kirwa et al. 2019) | Puerto Rico | Cohort R | 332,129 | PM2.5 (Ambient monitoring) | Entire pregnancy | Probably high |
| (Kumar 2012) | Chicago, USA | Cohort R | 400,000 | PM2.5, PM10 (Ambient monitoring) | Entire pregnancy, 1st, 2nd, and 3rd trimesters | Probably low |
| (Lamichhane et al. 2018) | South Korea | Cohort P | 648 | PM10 (Modeling) | 1st, 2nd, and 3rd trimesters | Probably low |
| (Laurent et al. 2013) | California, USA (2 counties) | Cohort R | 105,092 | PM2.5, PM10 (Ambient monitoring and modeling) | Entire pregnancy | High |
| (Lavigne et al. 2018) | Ontario, Canada | Cohort R | 196,171 | PM2.5 (Ambient monitoring) | Entire pregnancy, 1st, 2nd, and 3rd trimesters | Probably low |
| (Li et al. 2019) | Ningbo, China | Cohort R | 170,008 | PM2.5, PM10 (Ambient monitoring) | Entire pregnancy, 1st, 2nd, and 3rd trimesters | Probably high |
| (Mannes et al. 2005) | Sydney, Australia | Cohort R | 138,056 | PM2.5, PM10 (Ambient monitoring) | 1st, 2nd, and 3rd trimesters | Probably high |
| (Medeiros and Gouveia 2005) | São Paulo, Brazil | Cohort R | 311,735 | PM10 (Ambient monitoring) | 1st, 2nd, and 3rd trimesters | High |
| (Merklinger-Gruchala and Kapiszewska 2015) | Krakow, Poland | Cohort R | 84,842 | PM10 (Ambient monitoring) | Entire pregnancy, 1st, 2nd, and 3rd trimesters | Probably high |
| (Morello-Frosch et al. 2010) | California, USA | Cohort R | 3,545,177 | PM2.5, PM10, PM2.5–10 (Ambient monitoring) | Entire pregnancy, 1st, 2nd, and 3rd trimesters | Probably high |
| (Parker and Woodruff 2008) | USA (excluding Alaska and Hawaii) | Cohort R | 785,965 | PM2.5, PM2.5–10 (Ambient monitoring) | Entire pregnancy, 1st, 2nd, and 3rd trimesters | Probably high |
| (Parker et al. 2005) | California, USA | Cohort R | 18,247 | PM2.5 (Ambient monitoring) | Entire pregnancy | Probably high |
| (Pedersen et al. 2013) | 12 European countries | Cohort P | 74,178 | PM2.5, PM10, PM2.5–10 (Modeling) | Entire pregnancy | High |
| (Rahmalia et al. 2012) | Poiters and Nancy, France | Cohort P | 888 | PM10 (Modeling) | Entire pregnancy, 1st, 2nd, and 3rd trimesters | Probably high |
| (Rhee et al. 2019) | Boston, USA | Cohort R | 3,366 | PM2.5 (Modeling) | Entire pregnancy, 1st, 2nd, and 3rd trimesters | Probably low |
| (Salam et al. 2005) | California, USA | Cohort R | 3,901 | PM10 (Ambient monitoring) | Entire pregnancy, 1st, 2nd, and 3rd trimesters | Probably low |
| (Santos Vde et al. 2014) | São José dos Campos, Brazil | Cross-sectional | 21,591 | PM10 (Ambient monitoring) | 3rd trimester only | High |
| (Savitz et al. 2014) | New York, USA | Cohort R | 252,967 | PM2.5 (Modeling) | Entire pregnancy, 1st, 2nd, and 3rd trimesters | Probably low |
| (Schembari et al. 2015) | Bradford, United Kingdom | Cohort P | 9,067 | PM2.5, PM10 (Modeling) | Entire pregnancy, 3rd trimester only | Probably low |
| (Schwarz et al. 2019) | California, USA | Cohort R | 2,768,898 | PM2.5 (Ambient monitoring) | Entire pregnancy | Probably low |
| (Sellier et al. 2014) | Poiters and Nancy, France | Cohort P | 1,026 | PM10 (Modeling) | Entire pregnancy, 1st, 2nd, and 3rd trimesters | Probably low |
| (Stieb et al. 2016) | Canada | Cohort R | 2,781,940 | PM2.5 (Modeling) | Entire pregnancy, 1st, 2nd, and 3rd trimesters | Probably high |
| (van den Hooven et al. 2012) | Netherlands | Cohort P | 7,772 | PM10 (Modeling) | Entire pregnancy | Probably low |
| (Vinikoor-Imler et al. 2014) | North Carolina, USA | Cohort R | 322,981 | PM2.5 (Modeling) | 1st, 2nd, and 3rd trimesters | Probably low |
| (Winckelmans et al. 2015) | Flanders, Belgium | Cohort R | 525,635 | PM10 (Modeling) | Entire pregnancy, 1st, 2nd, and 3rd trimesters | Probably high |
| (Xiao et al. 2018) | Shanghai, China | Cohort R | 132,783 | PM2.5 (Modeling) | Entire pregnancy, 1st, 2nd, and 3rd trimesters | Probably low |
| (Xue et al. 2018) | USA | Cohort R | 18,317,707 | PM2.5 (Ambient monitoring) | Entire pregnancy | High |
| (Yang et al. 2003) | Kaohsiung, Taiwan | Cohort R | 13,396 | PM10 (Ambient monitoring) | 1st, 2nd, and 3rd trimesters | Probably high |
| (Ye et al. 2018) | Taizhou, China | Cohort R | 24,246 | PM10 (Modeling) | Entire pregnancy, 1st, 2nd, and 3rd trimesters | Probably high |
| (Yuan et al. 2020) | Shanghai, China | Cohort R | 3,692 | PM2.5 (Modeling) | Entire pregnancy, 1st, 2nd, and 3rd trimesters | Probably low |
R: retrospective cohort; P: prospective cohort