Hope Annis-Brown and Carl Morgan, who are both aged in their 20s, welcomed four baby girls on December 6, more than three months before their due date in February.

They also have a son together, Carl, who turns one on New Year's Day, and Ms Annis-Brown has a nine-year-old daughter from a previous relationship.

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The pregnancy was a very unexpected journey for the young couple, who didn't find out they would be having multiples until Ms Annis-Brown was 26 weeks along.

"We first thought it was triplets and then it turned into four," Mr Morgan said.

They learned of the fourth baby while delivering the children via caesarean section just two weeks later.

"I went into labour at 28 weeks and when I was in the surgery room they took out the three and the doctor felt under my ribs and said there was four," Ms Annis-Brown said.

She said she was "shocked" but "just went along with it".

Despite being born very early, the girls are doing just fine.

They have decided to name them Ariah, Aaliyah, Nataliah and Nariyah.

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Ms Annis-Brown is recovering well since her C-section, but the babies will need to stay in hospital for a while longer until they gain more weight.

When the family is able to return to Bathurst from Nepean Hospital, they will be moving in with Mr Morgan's mother.

While it has been a big shock, the couple say they are adapting to becoming parents of five children all under one year old.

"We're trying to get around being surprised and trying to be prepared," Ms Annis-Brown said.

"We've got a lot of support from family".