ABSTRACT
This chapter describes several mechanisms for the pathogenesis of preterm birth. Activation of the fetal hypothalamic-pituitary-adrenal axis, long hypothesised as a potential initiating mechanism in normal labour, may also be implicated in preterm labour. Assisted reproduction techniques are responsible for up to one third of twin pregnancies and three quarters of triplets, leading to an increasing burden of preterm births. In those pregnancies affected by higher-order multiples, multifetal reduction has been shown to reduce the risk of preterm birth and should always be considered. Serious infective illnesses such as pyelonephritis, appendicitis and pneumonia are associated with preterm labour. Intercurrent illness may also result in iatrogenic indicated preterm birth for maternal or fetal reasons. Owing to limited resources and a paucity of beneficial interventions in low-risk women, most aspects of prematurity prevention should be targeted at women with major risk factors for preterm birth.
