One member Merilene Horsford works in the hospital's Special Baby Care Unit, and explained how the premature babies need blankets of pure wool.
"Aunty Muriel started knitting and she kept going and going," Mrs van Engelen said.
Muriel Mengelberg, 87, has churned out 28 small blankets in just over year. Other members of the group do the crocheting around the edges of the blankets.
The group received a grant from Ngati Hau health and social services and used some of it to buy pure wool to knit the blankets.
The group also found old woollen blankets and cut them up into about 100 smaller ones, and they too got a crocheted edging.
Mrs Mengelberg has been knitting "since I started having babies of my own, 67 years ago".
She had eight children, and knitted for them all. Her daughter, Pauline Edwards, is also part of the group and remembers her mum pulling apart the boys' jumpers and re-using the wool for items for her and her sister.
Sara Smeath and Christopher Saunders from Maromaku, were two of the parents who received items for their newborn twins.
Their yet-to-be named twin girls, who are 17 days old and were born at 37 weeks and one day.
Ms Smeath said the donation was fantastic, especially because they weren't fully prepared for the extra warmth their premature babies needed.
The group has also been knitting hot water bottle covers to sell as a fundraiser.
They are always on the lookout for pure wool donations. If you can help, email whakapara@xtra.co.nz.