 Because the bowels of preterm infants have not matured, they cannot digest large volumes of milk feeds straight away. Until the gut matures, nutrition is provided by intravenous drip while the amount of milk given is gradually increased over time. Increasing the amount of milk rapidly may increase the risk of gut complications. Increasing the amount of milk given more slowly means that intravenous nutrition is needed for longer; there is an associated risk of infection proportional to the time the intravenous line is present in the bloodstream of these infants. Despite the importance of milk feeding preterm infants, there have been few studies to inform how best to balance these risks, and what the best way to increase feeds in these infants is - this study sets out to address this missing information. 