Preterm deliveries are increasing in absolute numbers and as a proportion of all births. According to NHS data for England in 2006, 2000 births—0.3% of all births—were extremely preterm (23-25+6 weeks’ gestation).1 Similar numbers are reported by other western European countries. Preterm births have increased by 20% over the past two decades in the United States, mainly because of the 42% increase in twin births.2 Advances in neonatal intensive care for babies born at the margins of viability have improved survival, but these infants are more likely to have long term morbidities and to use healthcare resources extensively in the first 2 years of life. Data from the Neonatal Research Network show that babies born before 26 weeks’ gestation spend at least 111 days in hospital during infancy and incur intensive care costs of more than £100 000 (€114 000; $160 000).3 An emotional and financial burden is often placed on families and community support systems. One or more family member may leave paid work to care for the baby, or skilled day care providers may help care for a child with serious ongoing medical conditions.4