Preterm labour

This course is part of the RCOG Core Knowledge series.

Preterm delivery, defined as delivery before 37 weeks of completed gestation, is a major cause of neonatal morbidity and mortality. Despite extensive research, preterm birth still accounts for 5–10% of all deliveries in developed countries and rates are on the increase.

In the UK about 8% of live born babies are born preterm. Most of these are born after 28 weeks of gestation but about 0.6% are born extremely preterm (22–28 weeks of gestation). It is also noteworthy that nearly 53% of liveborn multiple births are born preterm.

While the mortality associated with preterm delivery has declined due to use of antenatal steroids and improvements in neonatal intensive care, preterm babies still remain at risk of major complications. These include respiratory distress syndrome, necrotising enterocolitis, retinopathy of prematurity, sepsis, intraventricular haemorrhage, periventricular leucomalacia and long-term cognitive and sensory impairment. Two major determinants for the mortality and morbidity of babies born preterm are gestation at delivery and birthweight.

Prematurity carries significant cost implications to both healthcare services and society in general.

Preterm birth has a multifactorial aetiology. Approximately 75% of deliveries occur as a result of spontaneous preterm labour, while the remainder follow intervention for maternal or fetal disorders that place the mother or fetus at risk, such as pre-eclampsia, fetal growth restriction, maternal diabetes and placenta praevia or abruption.