Incorporating human milk fat supplement into premature infants' diets improves their growth outcomes in the neonatal intensive care unit (NICU), says a new study.

"For premature babies who weigh less than a kg, one of the problems is that their lungs and other organs are still developing when they are born," said Amy Hair, an assistant professor at Baylor College of Medicine in the US.

"If the infant gains weight and increases in length at a good rate while in the NICU, this helps improve their (growth) outcomes," Hair added.

Previous research has shown that an exclusive human milk diet protects the intestines of premature infants and supports their growth.

This diet consists of mothers' own breast milk or donor human milk, as well as a fortifier consisting of protein and minerals made from the donor milk.

In this study, researchers sought a way to optimise growth in infants who weigh between 750 and 1,250 grams and need additional calories.

As infants are already receiving enough protein from the fortifier, another way to help them grow is by giving them fat. One of the byproducts of pasteurising donor milk is milk fat, also referred to as a cream supplement.

They found that infants in the cream group had better growth outcomes in terms of weight and length than infants in the control group.

The study appeared in the Journal of Pediatrics.