Literature search and study selection
Searches of Ovid Medline, Embase, CENTRAL (The Cochrane Library), Cinahl and Emcare were carried out to identify studies reporting on race and PE. The search was carried out on the 10th August 2021 with no restriction for starting date but was restricted to English language records only; the initial search was updated with autoalerts in Medline to 31st December 2021. A list of relevant citations was generated from these databases using the search strategies given in Appendix 1. This review was registered in PROSPERO international database for systematic reviews (reference: CRD42021267548).
The abstracts of citations were examined by two reviewers (A.A. and D.V.) to identify all potentially relevant articles, which were then examined in full-text form. Reference lists of relevant original and review articles were hand-searched for additional reports. Agreement about potential relevance was reached by consensus and by consultation with a third reviewer (K.H.N.). The inclusion criteria were peer-reviewed studies reporting on PE in singleton pregnancies according to the racial origin of women so that the rate of PE could be compared in black and South and East Asian women to the rate in white women. We excluded twin pregnancies, case-control studies and review articles or guidelines and articles in which PE and GH were not given separately.