Preterm birth (PTB) is defined as the birth of a baby before the completion of 37 weeks gestation in the womb. It is the major cause of infant mortality particularly during the first month of life. Approximately 75 per cent of babies who die during the first 28 days of life are born before 37 weeks gestation. Survivors of PTB are at increased risk of long-term disabilities such as cerebral palsy, sight and hearing impairment, learning and behavioural problems, epilepsy, and hospital readmissions. Even late preterm births, defined as PTB at 34--36 weeks gestation, which account for 70% of all preterm births in England and Wales, are at increased risk of death and disability compared with babies born at term. Although the prevalence of adverse long--term outcome is highest among children born at the earliest gestational ages, the much higher number of births at 34--36 weeks of gestation compared with earlier gestations means that this group of children makes a major contribution to the number of children adversely affected. PTB and its consequences can have negative emotional and psychosocial impacts on parents and families.