Medline, PubMed, the Cochrane Database of Systematic Reviews, ACP Journal Club, and BMJ Clinical Evidence were searched for relevant articles, with concentration on randomized controlled trials (RCTs), systematic reviews, and clinical practice guidelines published between 1995 and 2007. Each article was screened for relevance and the full text acquired if determined to be relevant. Each full-text article was critically appraised with use of the Jadad Scale and the levels of evidence definitions of the Canadian Task Force on Preventive Health Care.
The quality of evidence was rated with use of the criteria described by the Canadian Task Force on Preventive Health Care.
The Society of Obstetricians and Gynaecologists of Canada.