Despite substantial advances in pre- and postnatal care, the problem of preterm labour continues to be a significant medical, economic and social burden. Globally, it is estimated that 13 million babies are born preterm each year, but the incidence varies substantially between different countries and population groups. In the United States alone, approximately 11% of pregnancies, i.e. 380,000 cases annually are delivered after preterm labour and in Europe the overall incidence is believed to be approximately 6%, representing an annual population of 375,000. The main complication of very early preterm birth to the newborn is immaturity of different organs, in particular incomplete maturation of the lungs. However, a recent multi-centre surveillance study demonstrated that also modest degrees of prematurity are associated with developmental delays, implying that adequate intrauterine maturation of the fetus is vital to postnatal development.