Table 1 Inclusion criteria
Domain | Inclusion criteria | Exclusion criteria | Elaboration |
|---|---|---|---|
Population | Human studies Reproductive and child health was defined as any timepoint from conception until 18 years of age, including studies of fertility | Reviews additionally examining other populations (i.e., unrelated adult populations) in addition that of interest were not included | This criterion was introduced to ensure the applicability and comparability of identified evidence grading approaches to studies of reproductive/ child health |
Exposure | All outdoor or indoor air pollutants (PM10, PM2.5, SO2, NO2, air toxics, biofuels, etc.) | Tobacco smoke, mold, wildfires, or allergens. Reviews examining other exposures in addition to air pollution were not eligible | To maximize the applicability and comparability of identified evidence grading approaches to studies of air pollution exposure, we considered only systematic reviews focusing solely in air pollution |
Outcome | All adverse reproductive or children’s health outcomes | Exposure levels, individual behaviors (e.g., physical activity) were not eligible endpoints | To ensure the comparability of systematic reviews, only those with an adverse health outcome as a primary endpoint were included |
Review design | Systematic reviews of observational studies. Only reviews considered “systematic”, based on the following reporting criteria were included [52]: (i) review question (ii) reproducible search strategy (e.g., naming of databases and search platforms/engines, search dates and complete search strategy) (iii) inclusion and exclusion criteria (iv) selection (screening) methods (v) critically appraises and reports the quality/risk of bias of the included studies (vi) information about data analysis and synthesis that allows the reproducibility of the results (vii) critically appraises and reports the quality of the body of evidence | Non-systematic literature reviews, scoping reviews, pooled studies, and meta-analyses not based on formal systematic review | Non-systematic reviews may be highly dissimilar in their objectives and methods compared to systematic reviews |
System for rating the body of evidence | Systematic reviews that explicitly used a published tool or framework to rate the quality of the body of evidence | Systematic reviews that did not explicitly use a tool, framework, or other published guidance for rating the body of evidence | For purposes of comparability, systematic reviews that did not rate the quality of the body of evidence, or that rated the quality of the body of evidence only as part of their discussion or in another informal manner were not included |
Timeframe | Articles published from 1995 onward were considered, | Published to any of the included sources before 1995 | Evidence rating was initially proposed as a stage of research synthesis in 1995 [10, 53] |
Language | English or German | All other languages | While systematic reviews in other languages may be relevant, we were not able to consider other languages due to resource constraints |