Premature birth is associated with increased perinatal morbidity and mortality. Spontaneous premature birth can be understood as a syndrome with a number of underlying causes including infection, maternal stress, uterine distention, placental hypoxia, bleeding and lack of prostaglandin dehydrogenase. Infection is probably the most important factor at low gestational age, with uterine distention and maternal stress increasing in significance further on. In the future we may become better able than we are at determining the specific reason in each individual case, which may lead to the development of more effective treatment. On the other hand, results have been very poor with respect to prevention, and in some countries we even note a slight increase in incidence. Although premature birth is often impossible to prevent, early detection and tocolytic therapy can delay labor long enough to permit effective corticosteroid therapy and transport when required to the appropriate obstetric clinic for optimal neonatal care.