| Ia | Evidence obtained from meta-analysis or systematic reviews of randomized controlled trials. |
| Ib | Evidence obtained from at least one randomized controlled trial. |
| IIa | Evidence obtained from at least one well-designed controlled study without randomization. |
| IIb | Evidence obtained from at least one other type of well-designed quasi- experimental study, without randomization. |
| III | Evidence obtained from well-designed non-experimental descriptive studies, such as comparative studies, correlation studies and case studies. |
| IV | Evidence obtained from expert committee reports or opinions and/or clinical experiences of respected authorities. |
Adapted from “Sign grading system 1999-2012,” by the Scottish Intercollegiate Guidelines Network (SIGN), 2012, in SIGN 50: A Guideline Developer’s Handbook. Available from http://www.sign.ac.uk/guidelines/fulltext/50/index.html
Women and Children
Working with Families to Promote Safe Sleep for Infants
Practice Recommendations