Preterm labour and birth

Context

Preterm birth is the single biggest cause of neonatal mortality and morbidity in the UK. Over 52,000 babies (around 7.3% of live births) in England and Wales in 2012 were born preterm (that is, before 37+0 weeks of pregnancy). There has been no decline in the preterm birth rate in the UK over the last 10 years.

Babies born preterm have high rates of neonatal and infant mortality, and the risk of mortality increases as gestational age at birth decreases. Babies who survive preterm birth have increased rates of disability. Recent UK studies comparing cohorts born in 1995 and 2006 have shown improved rates of survival (from 40% to 53%) for extreme preterm births (born between 22 and 26 weeks). Rates of disability in survivors were largely unchanged over this time period.

The major long-term consequence of prematurity is neurodevelopmental disability. Although the risk for the individual child is greatest for those born at the earliest gestational ages, the global burden of neurodevelopmental disabilities depends on the number of babies born at each of these gestations, and so is greatest for babies born between 32 and 36 weeks, less for those born between 28 and 31 weeks, and least for those born at less than 28 weeks gestation.

Around 75% of preterm births occur after preterm labour, which may or may not be preceded by preterm prelabour rupture of membranes. The remaining women giving birth preterm have an elective preterm birth when this is thought to be in the fetal or maternal interest (for example, because of extreme growth retardation in the baby or maternal conditions such as pre-eclampsia).

This guideline reviews the evidence for the best way to provide treatment for women who present with symptoms and signs of preterm labour, and women who are scheduled to have an early planned birth. It also reviews how preterm birth can be optimally diagnosed when symptoms are present, given that many women thought to be in preterm labour on a clinical assessment will not give birth preterm.

The guideline does not cover who should and should not have medically indicated preterm birth, or diagnostic or predictive tests in asymptomatic women.