5 - Abnormal labour

Summary

Introduction

Abnormal labour represents a large proportion of obstetric and anaesthetic work load on the labour ward.

Pre-term labour

Preterm labour is defined as the onset of spontaneous contractions before 37 weeks gestation. In current practice, intervention in the form of tocolysis would usually be considered in women presenting with contractions prior to 34 weeks gestation in view of the significant implications for perinatal morbidity and mortality in these cases. Preterm delivery is the leading cause of neonatal mortality. The survival rate of babies born in the developed world now ranges from 17 % for babies born at 23 weeks to over 90 % for babies born at 30 weeks. Mortality rates are directly related to both gestation and birthweight, with birth weight being a better predictor of survival after 29 weeks gestation. Multiple pregnancies are associated with poorer neonatal survival rates when compared to singleton pregnancies at the same gestation and neonatal mortality is significantly higher in male infants. In addition to neonatal mortality, prematurity is associated with significant long-term morbidity and disability. Significant ongoing motor impairment occurs in approximately 1 in 4 low-birth weight infants (< 1500 g) and approximately 1 in 3 have hearing or visual impairments. Premature and low-birth weight babies are also more likely to have chronic lung disease, require hospital admission for acute illness and develop cardiovascular disease in later life.

There are a number of identifiable risk factors associated with preterm labour, which are listed below.