We write to inform the Editors and the readership of Ultrasound in Obstetrics & Gynecology (UOG) that the article by El-Refaie et al.1, assessing the value of vaginal progesterone for the prevention of preterm birth in asymptomatic women with a twin gestation and a sonographic short cervix, was retracted on 27 July 2021 by the Editor-in-Chief of Archives of Gynecology and Obstetrics, Prof. Olaf Ortmann2. This article had been included in a systematic review and meta-analysis of individual patient data (IPD) that we published in UOG in 20173. Herein, we describe what has occurred and the implications to the conclusions of our article. The matter emerged after allegations of scientific misconduct were filed with Prof. Ortmann. The published paper stated that the study was conducted at the Mansoura University Hospital and in private practice settings in Mansoura, Egypt, and that the study protocol had been reviewed and approved by the Institutional Review Board (IRB)1. In May 2020, in response to a communication from some of the authors of the IPD meta-analysis, the authors of the trial and Prof. Abdelmageed Mashaly, the Chair of the Department of Obstetrics and Gynecology at Mansoura University Hospital at the time the protocol was approved and the study was conducted, represented that the study had been approved and endorsed by the Department and reviewed and approved by the IRB of the Mansoura Faculty of Medicine (copy of email communication and IRB approval document are available from the corresponding author on request). On 23 June 2020, Prof. Ortmann indicated that an investigation had been opened at Mansoura University in February 2020 given the allegations of scientific misconduct and that, during the ongoing investigation, the authors had described the regulatory review process and had submitted documents that met the requirements of the publisher. Specifically, Prof. Ortmann stated: ‘One critical point [raised in the allegation] was that ethical approval for the study did not exist. The investigators at Mansoura University describe[d] the regulatory process and provided documents. These are in accordance with the requirements of Springer [N]ature. We have followed the e-mail communication, which in the meanwhile is highly complex. Myself and the Research Integrity Team at Springer [N]ature treat this matter with high priority. We decided to wait for the final result of the investigation at Mansoura University.’ (copy of email communication is available from the corresponding author on request). Prof. Ortmann and the publisher have since changed their minds about the ethical approval and retracted the paper. The Notice of Retraction2 states that ‘Contrary to the statement in the article, the authors did not obtain approval from a research ethics committee before conducting the randomized control trial . . . ’. The authors did not agree with the retraction. The investigation at Mansoura University is still in progress. The paper published by our group in UOG is a systematic review and meta-analysis of IPD addressing the effect of vaginal progesterone in patients with a twin gestation and a short cervix3. The study was registered in PROSPERO (The International Prospective Register of Systematic Reviews) and identified previous randomized controlled trials (RCTs) that had addressed this question. The study by El-Refaie et al.1 met the eligibility criteria and was included. Our study described the methodology of the IPD meta-analysis, assessment of bias, planned sensitivity analysis and other details. We planned and carried out a sensitivity analysis by excluding studies at high risk of selection bias or performance and detection biases3. The study by El-Refaie et al.1 did not have a placebo group and, therefore, it was considered to be at high risk for performance and detection biases. The results of a sensitivity analysis excluding the trial of El-Refaie et al.1 were reported in the results section of our meta-analysis3. Moreover, the contribution of the trial by El-Refaie et al.1 to the conclusions of the meta-analysis, the limitations of the study and the implications for practice were described in the abstract and in the Discussion of our study3. An itemized description of the relevant statements in our paper is presented below. In addition, the original paper, as published in UOG, is provided in Appendix S1, and the relevant text is highlighted in yellow for the convenience of the interested reader.