Core Outcome Sets (COS) related to pregnancy and childbirth: a systematic review.

Background: Systematic reviews often conclude low confidence in the results due to heterogeneity in the reported outcomes. A Core Outcome Set (COS) is an agreed standardised collection of outcomes for a specific area of health. The outcomes included in a COS are to be measured and summarized in clinical trials as well as systematic reviews to counteract this heterogeneity.