Two mums with newborn babies, sharing a four-bedroom house with 16 others - that was the situation for two sisters, before they were referred by their midwife to an Auckland housing provider.

And advocates say the sisters' case is far from isolated, with more babies being born into overcrowded houses or to no home at all.

"I got my sister there and her husband and four kids, and the other sister and husband and seven kids, so heaps of people around there," said Polohivia Kaufusi, as she described her former home.

"And grandma too," her sister, Ahiahi Kaufusi, said.

In total, 20 people lived in the four-bedroom house.

"It was scary," Polohivia said, adding that she feared the crowded conditions would make her newborn baby ill.

The sisters came to New Zealand from Tonga in 2012, under the Pacific Quota Ballot system.

It was not until their midwife visited the house after their babies were born that they managed to change their living situation.

Distressed by what she saw, the midwife called Danielle Bergin, who runs Island Child Charitable Trust.

"They were in a single room, there was two newborn babies with their mums as well as two teenagers on bunks," Ms Bergin said.

"She rang me and she was just so worried. She said, 'Dani, it cannot happen. I cannot leave those babies in that environment.'"

Ms Bergin set up the non-profit organisation to support marginalised people in the greater Auckland area.

Her clientele never used to be homeless mothers with newborn babies, and it never used to be midwives that referred people to her, but such cases now made up the majority of her work, she said.

"Pretty much my last six cases over the last two months have been people with newborn babies.

"We rehomed a mum two days ago who was due that day to give birth," she said.

Barriers to getting help

Polohivia and Ahiahi Kaufusi had now found Housing New Zealand accommodation.

They, and their babies, were happy and healthy.

However, getting there was made tough by the language barrier - they had no idea how to ask for help in a strange new country.

Ms Bergin said their new life in New Zealand was worlds away from what they had in mind.

"They said, 'It's so hard.' They had no idea how hard it would be."

"Why don't we just portray the truth, you know?

"If you get a resident visa on a Pacific ballot scheme, be prepared to come to New Zealand and do it really hard. Because that's the reality."

Ms Bergin said babies being born into homelessness were yet another signpost of an ever-worsening housing crisis.

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