Eight hearing-test screeners have lost their jobs after more than 2000 newborns were not screened properly.
Letters have been sent to parents of 2077 infants after problems emerged with the newborn hearing screening programme.
Irregularities in the programme were detected at six district health boards - Auckland, Lakes, Bay of Plenty, Waitemata, Canterbury and Hutt Valley.
A 10-month-old boy who had to be retested was found to have congenital hearing loss and was now receiving treatment.
The programme screens about 55,000 newborns each year and expects to find one in 1000 with congenital hearing loss.
Upper Hutt mother Carissa Coulson's six-month-old son Tyler was one of 176 children in the Hutt Valley to be recalled for a retest.
Tyler was first screened as a newborn in hospital, but this did not give conclusive results. He passed a follow-up test in June when he was four weeks old.
Mrs Coulson then received a letter in August saying Tyler needed another test.
"I was really confused . . . I thought, ‘He's already been checked. Why am I getting a letter?'
"When I went down there to get him checked the lady told me not to worry, because there were a lot of people who were called up to come back down."
Tyler had shown no signs of hearing impairment - he looked when his name was called and jumped at noises, she said.
National Screening Unit group manager Jane McEntee said the national problem had been picked up in Auckland. "A baby was being screened and the parents said the baby had already had their hearing tested, but there were no results recorded in the system," she said.
"That prompted staff to look into the issue and these irregularities were subsequently found."
Eight hearing screeners had lost their jobs, but the 10-month-old was the only baby who had a delayed diagnosis as a result of the "irregularities", she said.
The retests occurred across six district health boards: Lakes (378 retests), Hutt Valley (176), Auckland (431), Canterbury (517), Bay of Plenty (542) and Waitemata (33).
After a baby is born, a specialist hearing screener will offer to test the baby's hearing.
It is up to parents to decide whether to agree to the free test, which is normally done before a baby leaves hospital or at a clinic appointment.
There are two types of tests, both painless.
One involves placing a small soft-tipped earpiece in the ear, which makes a soft clicking sound and measures how the ear responds.
The other involves placing ear cups over their ears, which play a soft clicking sound. Sensors on the baby's head measure how the ear and brain respond to the sounds. If a baby passes the test, the parents are given a results sheet.
If one or both ears do not show a clear result, the child is referred to a hearing specialist.
- The Dominion Post