Survival of preterm infants has increased greatly over the years, so a major aim now is to improve the long term outlook for these babies and to avoid serious complications. The way babies are fed in early life affects short and long-term health and survival.

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.

The study will compare two different speeds of milk feed increase, one 'faster' and one 'slower', both within rates currently used in United Kingdom neonatal units. The study aims to find out if either speed of milk feed increase gives better outcomes for the infants. Investigators will measure a variety of outcomes, such as survival without disability, infection, bowel problems, growth and long-term physical and mental development, as well as the impact on families and the National Health Service, including costs.

The study is being led by an established team of researchers who have run similar studies before, and uses an established network of neonatal units that have taken part in previous studies.

Inclusion Criteria:

• Gestational age at birth <32 weeks, or birth weight less than 1,500 g
• Receiving ≤30 ml/kg/day of milk at randomisation
• Written informed parental consent is obtained

To ensure the widest applicability to preterm infants across the United Kingdom, those exclusively breast milk fed, formula milk fed, or receiving mixed feeds will be included

Exclusion Criteria:

• Infants with a severe congenital anomaly
• Infants who, in the opinion of the treating clinician, have no realistic chance of survival
• Infants who are unlikely to be traceable for follow-up at 24 months of age corrected for prematurity (for example, infants of non-United Kingdom residents)