Pre-term labour

Abstract

Pre-term delivery often results from uncomplicated spontaneous preterm labour and accounts for 30% of low birth weight babies. Prematurity is the principle cause of a quarter of perinatal deaths; it is an associated factor in another quarter. Before 32 weeks maturity the newborn is at high risk, a major factor being the high incidence of respiratory distress syndrome (hyaline membrane disease), though ascending infection is also important, particularly if the membranes rupture prematurely. Before 34 weeks maturity there is some advantage to the newborn if premature labour can be arrested and delivery postponed, particularly if the amniotic fluid lecithin-sphingomyelin ratio is immature. After 34 weeks maturity there is little advantage to the newborn in arresting labour except in the small proportion of cases where the lecithin-sphingomyelin ratio is still immature.