Infants are usually unable to co-ordinate their suck, swallow and breathing before 33-34 weeks gestation and will likely require naso- or orogastric feeding at this time
Infants who are unwell or premature will need intravenous fluids in the short term and parenteral nutrition if unfed for long periods - this provides full nutrition via a central venous device.
Neonatologists will try to offer milk to infants born at all gestations, but feeds should be introduced cautiously and breast milk is the least likely feed to cause complications.
Specialist pre-term formulas exist for premature infants who may have additional protein, fat, vitamin, mineral and iron requirements.