Nine babies born with hearing losses, six of them moderate to profound, did not get the crucial early intervention they needed for normal speech and language development because of a screening blunder.
An industry insider believes the number of children with a hearing loss not picked up by the Universal Newborn Screening Programme could be far greater because only about 30 per cent of those recalled were rescreened.
National Health Board national services purchasing director Jill Lane said 6923 babies were recalled to hospital to have their hearing checked after the Ministry of Health discovered "irregularities" in its newborn screening programme.
Only 2234 were rescreened and nine were found to have hearing losses ranging from mild to severe.
One of the babies recalled, then 10-month-old Addison Blundell, was found to be profoundly deaf along with Ray Ruilin Yang from South Auckland, now 3.
Both children have bilateral cochlear implants while four other children have hearing aids.
Yesterday Associate Health Minister Jo Goodhew said two new reports into newborn hearing screening should give parents confidence in the programme. Problems with the programme included eight of 108 screeners either testing their own ears, the same ear twice on a baby, or only one of the baby's ears.
The irregularities came to light when Auckland District Health Board discovered a low detection rate in the numbers being screened.
An investigation found anomalies at six DHBs including Auckland, Waitemata, Bay of Plenty, Lakes (Taupo), Hutt Valley and Canterbury.
Waikato was also found to have irregular results between 2008 and 2012 and rescreened 377 toddlers, none of whom had hearing losses.
The programme was rolled out nationwide in 2010 and is intended to check the hearing of 60,000 babies born each year.
Auckland DHB director of child health Dr Richard Aickin said children who had not been rescreened and who had hearing loss would have come to someone's attention by now.
"These children are still being identified and still receiving treatment but we've missed a number of months in terms of being able to provide that earlier, so that's not great."
Lapse leaves toddler behind the play
Addison Blundell is 2 but the toddler has the speech and language ability of a 1-year-old.
The Lower Hutt girl's profound deafness was not diagnosed at birth as it should have been because a hearing screener tested her own ears instead of Addison's.
It meant Addison's congenital hearing defect was not picked up until she was 9 months old when she was called in by Hutt Valley District Health Board for rescreening because of the irregularities.
Her father, Rawiri Blundell, and mother, Kerrie Mackay, were shocked and furious when they found outthat the screener did not test Addison.
"Just absolute rage was what I felt when I found out," Mr Blundell said. "Reading the review there were complaints from some of the screeners that they felt underappreciated and underpaid and I can sympathise with that but it doesn't give you carte blanche to just be as unprofessional as that."
The 31-year-old information technology worker said he was also frustrated that health officials appeared to ignore warnings that monitoring the programme was crucial after ethically compromised screeners were caught doing the same thing in Britain.
"Did we really need to learn that mistake ourselves?"
Mr Blundell said he was satisfied with the recommendations to overhaul the system but it did not help Addison.
She received two cochlear implants just over a year ago after the family raised more than $27,000 for one of the surgically inserted hearing devices.
The cochlear implants mean that Addison can now communicate, and she understands sentences but her development has been delayed.
Mr Blundell hopes that by the time his daughter is 5 and goes to school she will have caught up to her "hearing peers" but there is no guarantee.