The consequences of preterm birth (PTB), to the individual and society at large, remain a major financial and personal burden. Babies born at the limits of viability, who survive, often have major neurological impairments, such as cerebral palsy, developmental delay and blindness. The cost of initial hospitalisation is more than $200 000 for each birth but takes no account of future costs once they leave the hospital. The major morbidities associated with extreme prematurity are respiratory distress syndrome (RDS), intraventricular haemorrhage (IVH) and necrotising enterocolitis (NEC). With advancing gestational age at birth, the financial costs and morbidity associated with these conditions decrease. The major morbidities (RDS, IVH and NEC) are rare by 34 weeks of gestation, with the exception of RDS, which complicates 7% of deliveries at this gestational age. While the vast majority of infants survive the first year of life, the infant mortality rate is markedly increased by three- to five-fold even for the mildly preterm infants, as compared with that of the term infants. Neonates born after 34 completed weeks of gestation rarely have mortality or major morbidity, but the financial costs remain significant ($7000 per case), and efforts to prevent delivery at this gestational age are probably indicated. Economic costs associated with PTB include the cost of initial hospitalisation, the cost of any chronic diseases resulting from the prematurity and social costs including loss of gainful employment by a family member taking care of the infant or child and loss of potential future earnings of the affected child. Antenatal steroids, if given to the mother at least 48 hours prior to a PTB, have shown significant reductions in RDS, IVH and NEC. Efforts to prevent, or avoid, PTB include the use of tocolytic agents which have been shown to prolong gestation for a minimum of 48 hours, or longer in some cases. The range of tocolytic agents used to delay or prevent PTB work through many different pathways, with varying degrees of success. Which tocolytic agent to use depends on many factors including underlying maternal status, gestational age of the fetus and documented efficacy of agent used.