More than 1500 children will be recalled to have their hearing checked by Hawke's Bay District Health Board.
They may have been incorrectly screened as part of the Newborn Hearing Screening Programme is finalised.
Paediatric clinical director Philip Moore said the 1524 figure was made up of 747 children who had been screened since 2008 and identified from the audit as not having been screened correctly.
The additional 777 were babies who had been born in the past six months.
"We have been overly cautious and are recalling all babies screened in the past six months as well, as we can't say for sure that they have been correctly screened," Dr Moore said.
He was confident the chance of a baby with a congenital hearing loss being missed was low.
Babies who had either been admitted to the Special Care Baby Unit, born prematurely or who had a known risk of congenital hearing loss were given a different screen and were, therefore, not at risk and not part of this recall, Dr Moore said.
Parents would be sent out letters, on a staggered basis, during the next 12 weeks offering appointments to have their child's hearing rescreened. Parents were urged to take up this offer, he said.
Hawke's Bay had identified a large number of children to be rescreened.
It was the first District Health Board to begin the screening programme, and had three screeners working who screened the 120 or so babies born each month.
Parents who were concerned could see their GP or WellChild Tamariki Ora provider or could call 0800 643 745 for more information.