Preterm labour and delivery.

Preterm birth is a major cause of perinatal morbidity and mortality. It accounts for 5-10% of all births, and any treatment to prevent it could have a profound effect on neonatal outcome in both human and economic terms. The pathogenesis of both term and preterm birth remain poorly understood. Our ability to predict those at risk of preterm labour is also inaccurate, despite the creation of scoring systems, uterine activity monitoring, cervical ultrasound and several biochemical markers. Current drug therapies for preterm labour have not been shown in randomised controlled trials to significantly affect perinatal morbidity and mortality. Furthermore, most are associated with significant maternal or fetal side effects. Nitric oxide (NO) is a potent smooth muscle relaxant, produced when NO synthase acts on the amino acid L-arginine. Its presence has been demonstrated in human myometrium. We have conducted an observational study which has suggested that glyceryl trinitrate (GTN), and NO donor, may be effective in prolonging gestation. A randomised trial comparing GTN to intravenous ritodrine is currently recruiting patients; results will be available in the Spring of 1997. Few side effects have so far been encountered. Evidence suggests that GTN, an NO donor, should be a safe and effective tocolytic and early observations are encouraging; randomised trials currently underway should determine the significance of this breakthrough in the management of preterm labour.