Abbreviations: ACOG: American College of Obstetricians and Gynecologists; AGREE II: Appraisal of Guidelines for Research and Evaluation II; CPG: clinical practice guideline or guidance; NICE: National Institute of Health and Care Excellence; NHLBI: National Institutes of Health, National Heart, Lung, and Blood Institute; and RCOG: Royal College of Obstetricians and Gynaecologists.