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

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.

The aim is to identify, compile and assess final and ongoing studies that are prioritizing outcomes in the area of pregnancy and childbirth.

All studies which prioritized outcomes related to pregnancy and childbirth using consensus method, including Delphi surveys or consensus meetings were included. Searches were conducted in Ovid MEDLINE, EMBASE, PsycINFO, Academic Search Elite, CINAHL, SocINDEX and COMET databases up to June 2021. For all studies fulfilling the inclusion criteria, information regarding outcomes as well as population, method, and setting was extracted. In addition, reporting in the finalized studies was assessed using a modified version of the Core Outcome Set-STAndards for Reporting.

In total, 27 finalized studies and 42 ongoing studies were assessed as relevant and were included. In the finalized studies, the number of outcomes included in the COS ranged from 6 to 51 with a median of 13 outcomes. The majority of the identified COS, both finalized as well as ongoing, were relating to physical complications during pregnancy.

There is a growing number of Core Outcome Set studies related to pregnancy and childbirth. Although several of the finalized studies follow the proposed reporting, there are still some items that are not always clearly reported. Additionally, several of the identified COS contained a large number (n > 20) outcomes, something that possibly could hinder implementation. Therefore, there is a need to consider the number of outcomes which may be included in a COS to render it optimal for future research.