Sirenomelia: A Review of European Prevalence Data and Epidemiological Analysis of 17 Cases Registered in Wales

Emmerson, Chris, Michael, Olson, Williams, Ceri, Maddison, Robert and Tucker, David 2026. Sirenomelia: A Review of European Prevalence Data and Epidemiological Analysis of 17 Cases Registered in Wales. Birth Defects Research 118 (5) , e70051. 10.1002/bdr2.70051

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Abstract

Background: Sirenomelia is a rare congenital condition most notably characterized by a single lower limb. Previous studies have suggested a prevalence of approximately 1 per 100,000 births. However, in Wales 17 cases were recorded between 1998 and 2016, suggesting a higher rate of sirenomelia in this country. Objectives: This study compared current prevalence of sirenomelia in Wales with European data. This study further reviewed detailed time, place, and person data on sirenomelia cases in Wales to investigate possible causal factors. Method: A retrospective cohort study from birth defect surveillance programs. Individual‐level records for all welsh cases were examined for evidence of causal factors. Comparator data from other countries were obtained from EUROCAT (a European network of population‐based registries for the epidemiological surveillance of congenital anomalies). Results: European data from 24 national and regional registries of congenital anomalies included 97 cases of sirenomelia identified across 9.6 million births between 1998 and 2016, giving a prevalence rate of 1 per 100,000 (95% CI 0.83, 1.23). Five regions reported statistically significantly higher rates than that recorded across all registries, while one region reported a significantly lower rate. Small numbers of cases limit definitive statistical interpretation. Analysis of the Wales data did not identify common epidemiological factors between cases. Conclusions: The contemporary prevalence of sirenomelia across Europe is consistent with earlier studies at approximately 1 per 100,000 births (95% CI 0.83, 1.23). However, there is greater variation between regions than would be expected by chance. There remains no definitive evidence for causal environmental factors.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Schools > Medicine
Additional Information:	For full list of authors please see artiucle webpage https://doi.org/10.1002/bdr2.70051
Publisher:	Wiley
ISSN:	2472-1727
Date of First Compliant Deposit:	13 May 2026
Date of Acceptance:	24 April 2026
Last Modified:	13 May 2026 09:15
URI:	https://orca.cardiff.ac.uk/id/eprint/186971

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