Risk of bias for the included studies
| Random sequence generation | Allocation concealment | Blinding of outcome assessment | Incomplete outcome data | Selective reporting | Other bias | |
|---|---|---|---|---|---|---|
| Anderson 2015 | Yes | Unclear | Unclear | Yes | Yes | Yes |
| Aubin 2006 | Unclear | Unclear | Unclear | Yes | Unclear | No |
| Berry 2011 | Yes | Yes | Unclear | Yes | Yes | Yes |
| Berry 2014 | Yes | Yes | Unclear | Yes | Yes | Yes |
| Bertsche 2009 | No | No | No | Yes | Yes | No |
| Cleeland 2011 | Yes | Yes | No | Yes | Yes | Yes |
| De Wit 2001 | Unclear | Unclear | Unclear | Yes | Yes | Unclear |
| Du Pen 1999 | Yes | Unclear | Yes | Unclear | Yes | Yes |
| Given 2004 | Yes | Yes | Yes | Yes | Yes | Yes |
| Hoekstra 2006 | Unclear | Unclear | Unclear | Unclear | Yes | Unclear |
| Kravitz 2011 | Yes | Yes | Unclear | Yes | Yes | Yes |
| Kroenke 2010 | Yes | Unclear | Yes | Yes | Yes | Yes |
| Miaskowski 2004 | Unclear | Unclear | No | Yes | Yes | Unclear |
| Mooney 2013 | Yes | Yes | Yes | Yes | Yes | Yes |
| Post 2013 | Unclear | Unclear | Unclear | Yes | Yes | Yes |
| Ruland 2010 | Yes | Yes | Yes | Yes | Yes | Yes |
| Rustoen 2012 | Yes | Unclear | Unclear | Yes | Yes | Unclear |
| Trowbridge 1997 | Unclear | Unclear | No | Unclear | Unclear | Unclear |
| Vallières 2006 | Unclear | Unclear | No | Unclear | Unclear | No |
| Van der Peet 2009 | Yes | Unclear | Unclear | Yes | Yes | Unclear |
| Velikova 2004 | Yes | Yes | Yes | Yes | Yes | Yes |
| Wilkie 2010 | Yes | Yes | Yes | Yes | Yes | Yes |