Retraction Statement

The article "Use of Intramuscular Progesterone versus Intravenous Albumin for the Prevention of Ovarian Hyperstimulation Syndrome" [Gynecol Obstet Invest. 2000;50(3):182-185; https://doi.org/10.1159/000010306] by Loredana Costabile, Vittorio Unfer, Claudio Manna, Sandro Gerli, Dario Rossetti and Gian Carlo Di Renzo has been retracted by the Publisher and the Editors.After publication of this article, concerns were raised about the uneven group sizes following randomization, the reported rate of pregnancy following transfer, which was higher than described in contemporary global statistics, and the significant difference between groups in the number of oocytes retrieved, though the differential intervention occurred post-retrieval. These raised concerns about the study's randomization. When asked to comment, the authors stated that they cannot address the concerns due to the fact that the article was published more than 25 years ago and data and documents are no longer available.The concerns raised and the authors' response were reviewed by the Editors. As the concerns, which may impact the reliability of findings presented in the article, cannot be addressed or resolved, and due to the relevance of the difference between the groups for the conclusions of the study, the article is being retracted.Vittorio Unfer does not agree to the retraction. Sandro Gerli stated that he bears no responsibility for this article. The remaining authors did not respond to the notification about this retraction within the timeframe specified.