Born just a few weeks early: does it matter?

Until recently, infants born at moderate preterm (32-33 weeks) and late preterm (34-36 weeks) gestations have gone largely unstudied. Since their outcomes were thought to be similar to those of infants born at 37 weeks and above, they have historically been managed in much the same way as infants born at term. However, accumulating data indicate that risks of morbidity and mortality are significantly greater in this group than previously believed. Since moderate and late preterm infants account for around 6% of all births, very large numbers of babies are potentially affected. Although their problems may be less obvious than those of extremely preterm infants, the population impact of long-term health and neurodevelopmental problems in this group will be substantial. This review summarises the current available literature, highlights gaps in knowledge and discusses the implications of late preterm birth for both clinical practice and research in the perinatal period and beyond.