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A leading authority on shaken baby syndrome says the level of child abuse in New Zealand is staggering, with nearly one child a week admitted to Auckland's Starship Hospital with serious physical injuries.

Hospital data, released to the Herald on Sunday under the Official Information Act, shows that since 2001, 181 children have been hospitalised as a result of "suspected or definite" child abuse. Of those, 13 have died.

The release of the figures comes a fortnight after a newborn baby was found dead in the backyard of a Lower Hutt home.

The Lower Hutt mother charged with murdering her newborn daughter has been remanded to a mental institution for psychiatric assessment.

Dr Patrick Kelly, the clinical director of Auckland's Starship Hospital child protection team, said child abuse had an enormous cost on society, not just economically but also socially.

"You look at the cost to families - the disruption and heartache and then on top of that the prosecution costs and the recriminations afterwards," Kelly said.

New Zealand's national diagnosed rate for head injuries to infants under the age of 2 caused by child abuse is 22 per 100,000 - which is comparable to the rest of the world.

However, for Maori children the figure is the highest in the world. Between 50 and 60 Maori infants per 100,000 suffer head injuries as a result of child abuse.

At Starship Hospital - the country's largest paediatric hospital - the 12 months to June 30 last year were the worst on record for child abuse admissions. In those 12 months, 48 children were hospitalised with physical injuries that were a result of suspected or definite child abuse. Seven of them died, a figure Starship said was unusually high. Most cases involved children under 1 year old.

In the 12 months to June 30 this year, there has been a slight decrease in the number of admissions, but the figure is still much higher than previous years.

Of the 38 suspect hospital admissions, 25 were for children with "non-accidental head injuries" and "non-accidental injuries".

The others were for children with possible injuries caused by child abuse. Of those children admitted, one later died.

These figures do not include cases where child abuse was suspected but later excluded.

Auckland District Health Board chief executive Garry Smith told the Herald on Sunday that children with head injuries generally had a broken skull or injury within the skull. All cases were referred to Child Youth and Family and police.

Kelly said many victims of child abuse were never seen by health authorities, and some would suffer undiagnosed brain damage for life.

Although injuries varied, generally those children who were hospitalised suffered from bleeding inside their head and retinal haemorrhaging - both classic symptoms of shaken baby syndrome.

These children often had been shaken or slammed against something solid, or in some cases punched in the head after being "caught in the crossfire" during a domestic dispute, Kelly said.

If they did survive the blow, about a third ended up with severe neurological handicaps such as spastic quadriplegia or blindness.

Another third had a moderate degree of disability such as weakness or loss of function on one side of the body.

Of the remaining third of victims, it was difficult to assess what damage had been caused to the brain, with many developing normally in their preschool years, but getting into difficulty later in life.

"A majority of those survivors will have some neurological handicap as a result of this abuse," Kelly said.

"The level of abuse is staggering especially when you take into account only 10 per cent of cases are in-patients."