Inclusion Criteria:  Preterm infants fed own mother's milk (or donor human milk) requiring HMF (as decided by the investigator) Born before 37 weeks completed gestational age and >1 dropped centile since birth requiring HMF (as decided by the investigator) Tolerating adequate volume of enteral nutrition Expected to require HMF after discharge (minimum 4.0g NHMF per day at discharge) Written or electronic informed consent from parent/caregiver  Exclusion Criteria:  Anticipated short term use of HMF leading to discontinuation of HMF after hospital discharge Presence of any relevant proven or suspected chromosomal anomaly or genetic syndrome, any gastrointestinal malformation/compromise, including Necrotising enterocolitis (NEC) (defined as Bell's stage two or higher), metabolic disorder, or congenital central nervous system malformation that may impact tolerance of enteral feeding Failure to establish enteral nutrition and requiring full parenteral nutrition Participation in other studies within 1 month prior to the entry of this study Known allergy to any of the study product ingredients, including cow's milk, fish and egg Concern or issues around the breast milk supply from mother of preterm infant at enrolment Investigator concerns around willingness/ability of the parent/caregiver to comply with protocol requirements and/or handle and store NHMF appropriately