BACKGROUND: The UK Obstetric Surveillance System (UKOSS) was established in 2005 for research into uncommon disorders of pregnancy. This study explored the use in policy and clinical guidelines of evidence generated through UKOSS during its 20-year history, in order to inform approaches to increase the impact of future studies conducted through the platform. METHODS: We searched Overton (24 September 2025) and Altmetric (6 October 2025) using the DOIs of articles reporting research conducted using UKOSS to identify citations in clinical guidelines and policy documents. We summarised citation frequency and characteristics of citing documents and organisations, and calculated the time between article publication and citation. For the most highly-cited articles, we explored the context of citations in a series of case studies. RESULTS: A total of 308 unique citations of the 96 articles reporting UKOSS studies were detected, and 62/96 articles (65%) were cited in at least one policy document or clinical guideline. A third of citations were by organisations based in the UK and Ireland, and citations were roughly evenly split between clinical guidelines (53%) and policy publications (46%). The median delay between publication of an article and citation in policy documents/guidelines was 220.8 weeks (range 0.3-904.7 weeks). The context of citations varied, and included providing rationale for specific clinical recommendations such as prioritisation of pregnant women for vaccinations and management of the conditions investigated; supplying evidence for equality guidance and impact assessment; and providing more general background on risk, burden, and/or outcomes. CONCLUSIONS: Evidence from studies conducted via the UKOSS platform has been used extensively in policy documents and clinical guidance in the UK and globally. Consideration should be given to how to speed up knowledge translation to allow pregnant women and their babies to benefit from evidence-based policies and practice with minimum delays.