Preterm or premature birth is when a baby is born before 37 weeks of pregnancy. In the UK, around 1 in 10 babies are born preterm. Most obstetricians and neonatal doctors will be more concerned when the premature birth occurs before 34 weeks and certainly before 32 weeks of pregnancy (very preterm). This is because the earlier the baby is born, the higher the risk of long term complications or health concerns for the baby.