Infection and preterm labour

Preterm labour occurs in up to 10% of all births but is associated with 85% of perinatal deaths in otherwise normal babies and an unknown proportion of physical and mental handicap. The cause of preterm labour is usually unknown. Cases associated with multiple pregnancy, polyhydramnios or abnormalities of the uterus or cervix are in the minority. Associations have been found between preterm labour and maternal age, weight and height, cigarette smoking, parity, and other socio-economic factors.’ Recently the role of infection has been recognised as a major factor in the aetiology of preterm labour. The evidence that preterm labour is associated with genital tract infection falls into three categories; the increased incidence of puerpural sepsis following preterm delivery; the increased incidence of infection in premature neonates; and the epidemiological association between preterm labour and genital tract colonisation by various organisms. The incidence of maternal puerpural sepsis is three-fold greater following preterm labour than delivery at term. The incidence of infection in premature neonates is 5% compared to O.l-0.5% in term infants.3 This is partly a reflection of their immaturity, their increased risk of instrumentation and exposure to hospital pathogens in the neonatal intensive care unit. It is likely, however, that many of these infections are acquired in utero or during vaginal delivery. Common causes of neonatal sepsis are the group B streptococci and Escherichia coli both of which are commonly found in the vagina.