Matta N, Young D, Boulton R, Mactier H. Survival of extremely preterm infants. Arch Dis Child Fetal Neonatal Ed 2010;95:f151–152. The authors have noticed a calculation error in their letter. The first sentence in paragraph 3 should read “the number of recorded live births <26 weeks' gestation as a percentage of total live births varied between the three maternity units from 0.20 – 0.26. (Not 8-11 per 10,000 live births as stated). The authors believe this does not affect the conclusions of their letter and would like to apologise for this error.