Prospective surveillance study of severe hyperbilirubinaemia in the newborn in the UK and Ireland.

To determine the incidence of severe hyperbilirubinaemia in the newborn, and to identify associated clinical and demographic variables, and short-term outcomes. Prospective, population-based study. UK and Republic of Ireland, between 1 May 2003 and 31 May 2005. Infants in the first month of life with severe hyperbilirubinaemia (maximum unconjugated serum bilirubin >/=510 micromol/l). 108 infants met the case definition, 106 from the UK and 2 from the Republic of Ireland. The UK incidence of severe hyperbilirubinaemia was 7.1/100 000 live births (95% CI 5.8 to 8.6). Only 20 cases presented in hospital; 88 were admitted with severe jaundice. 64 (60.4%) cases were male, and 56 (51.8%) were of ethnic minority origin. 87 (80.5%) cases were exclusively breast fed. Co-morbidity included haemolysis, dehydration, infection and bruising. 14 infants showed evidence of bilirubin encephalopathy, of whom 3 died. The UK incidence of bilirubin encephalopathy was 0.9/100 000 live births (95% CI 0.46 to 1.5). This is the first large, prospective, population-based study of the incidence of severe hyperbilirubinaemia in the newborn. The clinical and demographic associations, and short-term outcomes identified, are the same as those reported recently in North America and Europe.