Background: Methodological and reporting assessment tools have been developed which allow us to investigate the core outcome set development process Objective: To characterise core outcome sets relevant to women’s and newborn health and assess methodological and reporting quality. Search Strategy: Systematic search using the Core Outcome Measures in Effectiveness Trials (COMET) and the Core Outcomes in Women’s and Newborn Health (CROWN) Initiative databases from inception to March 2020. Selection Criteria: Registered, progressing, and completed core outcome sets. Data Collection and analysis: Descriptive summaries of characteristics and results. Published protocols were assessed using the Core Outcome Set-STAndardised Protocol Items (COS-STAP). Completed core outcome sets were evaluated using COS-STAD (standards for development) and COS-STAR (standards for reporting). Main Results: Eighty studies were identified. Twenty-four studies had published a protocol; four (17%) met all COS-STAP criteria. This was primarily due to poorly defined steering groups and lack of discussion around the potential impact of attrition. Thirty-nine systematic reviews characterized inconsistency in outcome reporting. Twenty studies published a core outcome set development process with four (20%) and three (15%) meeting COS-STAD and COS-STAR recommendations respectively, largely due to variation in patient involvement, outcome selection and the Delphi process Conclusions: Future core outcome set developers should actively engage with the methodological and reporting criteria to enhance the quality of their studies. Clarity is also required within the assessment guidelines as to how these issues should be adequately addressed. We have identified 5 key areas for improvement for future core outcome set developers and wider stakeholders

Sir, We would like to thank Sharma and colleagues for their interest in our recent study evaluating the effectiveness and safety of surgical interventions for Bartholin’s cyst or abscess.1Their response highlights the unique opportunity offered by randomised trials, and their syntheses into meta‐analyses, to assess patient reported outcomes. We would strongly encourage researchers to select, collect and report patient reported outcomes in future research evaluating interventions for Bartholin’s cyst or abscess.2The primary outcome should be the outcome of greatest therapeutic importance to the study’s prospective hypothesis. There is currently no consensus regarding the selection of outcomes and methods of definition or measurement for randomized trials evaluating interventions for Bartholin’s cyst or abscess.3 In the absence of a standardized approach, researchers have made arbitrary decisions when choosing among several important outcomes.4 It would be useful for healthcare professionals, researchers, and women with lived experience of Bartholin’s cyst or abscess to engage in a formal consensus development process to agree appropriate primary and secondary outcomes.3We agree the use of adjuvant antibiotics is an important consideration. They were not reported by any of the included trials.5We have no experience of marsupialization performed under local anaesthetic. In our opinion, this approach would need to be evaluated within a research setting. The recent COVID-19 pandemic would provide additional impetus to undertake this much needed research.James M. N. Duffy 1,2, Emma Kirk 3, BJG Illingworth 4, K Stocking 5,Marian Showell 61 Institute for Women’s Health, University College London, London, United Kingdom.2 King’s Fertility, Fetal Medicine Research Foundation, London, United Kingdom.3 Department of Obstetrics and Gynaecology, Royal Free London NHS Trust, London, United Kingdom.4 North West Anglia NHS Foundation Trust, Peterborough City Hospital, Peterborough, UK5 Centre for Biostatistics, Division of Population Health, Health Services Research and Primary Care, University of Manchester, Manchester, UK6 Cochrane Gynaecology and Fertility Group, University of Auckland, Auckland, New Zealand.

Abstract Objective: To develop a core outcome set for trials investigating interventions to prevent stillbirth. Design Outcomes identified from a systematic literature review and semi-structured interviews with parents were entered into a two-round online Delphi survey. Setting and population Australia and UK Methods: Delphi survey and focus group/consensus meetings Results: A core outcome set containing 11 outcomes in two categories. Five outcomes were related to the mother; fetal loss (to include both miscarriage and stillbirth), onset of and mode of delivery (to include induced/spontaneous and instrumental/vaginal/CS), maternal mortality or near miss (according to WHO definition), psychological and social impact on the mother (assessed using a validated tool appropriate to context), women’s knowledge. Six outcomes were related to the baby; timing of stillbirth (antepartum/intrapartum), neonatal mortality, gestational age at delivery, birthweight (g), congenital anomaly, NICU/SCBU or other higher-level neonatal care length of stay (days). Conclusion Implementation and dissemination of this core outcome set in future trials will contribute towards coordinated outcome reporting and advancing usefulness of research to guide clinical practice. Keywords: Core outcomes, core outcome set, Stillbirth, Delphi

Sir,We read with great interest the recent study by Misra et al.evaluating different surgical interventions for the treatment of pain associated with endometriosis.1 We understand the importance of this research to inform our clinical practice and extend our gratitude to the researchers, the women who participated in the study, and the research funder.BJOG: An International Journal of Obstetrics and Gynaecology has been at the forefront of reducing research waste by implementing several important interventions including the requirement to prospectively register randomised trials, implementing the Consolidated Standards of Reporting Trials (CONSORT) statement, and mandating the reporting of core outcome sets.2Reflecting upon this recent study presents an opportunity to consider the impact of implementing such initiatives on selective outcome reporting. The authors prospectively registered their trial (ISRCTN50928834) and reported their pre-specified primary outcome as pelvic pain. This differs from the primary outcome reported in the final publication. A secondary outcome, dyspareunia, reported in the final publication, was not prospectively registered. The CONSORT statement commits researchers to report all prespecified primary and secondary outcomes. When new outcomes are added this should be made clear in the final publication and a comprehensive explanation provided. It would be useful for the authors to clarify the discrepancies between the prospective registry record and the published trial report.Core outcomes aim to address the challenges of poorly selected, collected, and reporting outcomes, including tackling outcome reporting bias.3 We are grateful to the authors for acknowledging the development of a core outcome set for endometriosis research within their study report. The core outcome set for endometriosis has recently been published and was developed using formal consensus methods involving 116 healthcare professionals, 32 researchers, and 206 women with endometriosis from 29 countries.4 The core outcomes include overall pain, improvement in most troublesome symptom, quality of life, adverse events, and patient satisfaction with treatment. It would be useful for the authors to clarify if the core outcomes had been collected as part of the trial and report available data.Over eighty speciality journals, including the Cochrane Gynaecology and Fertility Group, have committed to supporting the development, dissemination, and implementation of the core outcome set for endometriosis. The collaboration who have developed the core outcome set for endometriosis are now assisting with implementation and are systematically examining published endometriosis trials. Where inconsistencies between the trial registry record and the outcomes reported in the published trial report are identified or when the core outcome set has not been fully reported we are writing to the authors seeking clarification. Our progress can be followed at https://twitter.com/EndoOutcomes where we will be posting the prospective registry record, final publication, and response to this letter.