Sources
We reviewed all studies registered with the COMET and CROWN initiatives from inception (2010) through to March 2020 (figure 1). COMET is a registry of COS studies, including citations to relevant protocols, systematic reviews, and completed core outcome sets. Studies are categorised by pre-defined ‘disease categories’ or ‘disease names.’ We included all disease categories to identify all studies related to women’s and neonatal health. The register is maintained by searches of the Cochrane Methodology Register, MEDLINE, and Scopus, with core outcome developers also encouraged to register prospectively.(7, 12) The CROWN initiative maintains an informal database which encourages core outcome developers to register their study.(12)