Omphalocele prevalence and co-occurring malformations: a nationwide register-based study of Danish live births in 1997–2021

Purpose Omphalocele is a congenital abdominal wall defect associated with a high risk of morbidity and mortality, with co-occurring congenital malformations often being the most important prognostic factor. High rates of spontaneous and medical terminations have been reported among pregnancies with omphalocele and co-occurring malformations. Few studies have focused on co-occurring malformations, particularly non-gastrointestinal malformations among live births. This study examined birth prevalence of omphalocele and co-occurring major malformations among a 25-year Danish liveborn cohort. Methods This nationwide retrospective prevalence study used data from the Danish National Patient Register and Danish Civil Registration System for infants who were delivered in Denmark during 1997–2021 and included in the Danish neonatal screening biobank. Diagnoses of omphalocele and co-occurring malformations were ascertained and prevalence estimated using Poisson regression. Results Among 1,498,685 live births, 147 infants with omphalocele were identified, yielding a combined and stable prevalence (per 10,000 infants) of 0.98 (95% CI 0.83–1.15). Over one-half (53.7%) presented with one or more major malformations, and an additional 17.0% were diagnosed with a syndrome. Conclusions Omphalocele birth prevalence in Denmark was stable over a recent 25-year period. The proportion of infants with co-occurring major malformations or diagnosed syndrome has important implications for long-term healthcare demands.