The lack of cots in the hospital's special-care nursery forced the transfer of his mother to the Mercy Hospital, where Hudson was born last month.

Now a $4.2million expansion of the nursery will raise the number of cots from six to 20.

On a visit to the construction works last week, Monash Children's medical director Professor Nick Freezer said the expansion would reduce the need to transfer newborn babies requiring extra care to other hospitals.

Hudson, still hooked up to tubes in his humidicrib

, weighed just 1556 grams when he was born - about half the weight of a full-term baby.

First-time mother Kellie has to express milk for Hudson to be intravenously fed. She travels daily to the hospital to deliver milk and spend a couple of hours by Hudson's side.

"It's amazing but I do nothing but watch him.

"He's tiny, but he's going well - he'll start to feed when he reaches 36 weeks."

Southern Health acting chief executive Siva Sivarajah said the expansion would help meet the growing demand for maternity services in the Casey-Cardinia growth corridor.

The expansion will also make way for consulting suites with areas for health promotion, education and advocacy for families of seriously ill babies.