Children's "vulnerability" is more like a revolving door than a fixed state, a new report has found.
The report from the Growing Up in New Zealand study, which is tracking 6500 children born in Auckland and the Waikato in 2009-10, says many children who were counted as "vulnerable" on the basis of 12 risk factors when their mothers were pregnant had already lost those risk factors by the time they turned 2.
Conversely, other children who did not have risk factors in pregnancy had acquired them by their second birthdays.
"We are seeing huge mobility in and out of exposure categories," said study director Dr Susan Morton.
"While the numbers at any point in time may look stable across a population, the actual individual children who are included are showing quite a degree of change."
The report raises doubts about a key element of the Government's vulnerable children's action plan - a proposal to identify vulnerable children through "predictive risk modelling" so that services can be wrapped around their families before any abuse or neglect occurs.
The study recorded 14 possible risk factors for mothers in pregnancy and at nine months and two years after giving birth: depression, poor physical health, smoking, drinking, age under 20, separation from partner, poor schooling, financial stress, unemployment, welfare dependency, frequent moving, and living in public rental housing, overcrowded conditions and low-income areas.
It found that drinking and frequent moving were not useful risk factors in New Zealand because all groups moved frequently and more advantaged mothers were actually more likely to drink alcohol than those who seemed disadvantaged.
The other 12 factors all clustered together so they seemed to identify a "vulnerable" group.
But the group turned out to be unstable.
Out of 909 mothers who were depressed in pregnancy, only 272 were still depressed nine months after giving birth. But 336 mothers who were not depressed in pregnancy had become depressed at nine months.
Out of 1062 mothers who were on benefits at nine months, only 673 were still on benefits at two years. But another 307 who were not on welfare at nine months had gone on to it by two years.
Sole-parenthood was also unstable. A majority of those who were sole parents at nine months had partners in pregnancy, and a majority of those who were sole parents at two years had partners at nine months.
The report found that babies whose mothers had two or more risk factors in pregnancy were 57 per cent more likely than other babies to have suffered an accident or injury needing medical attention in their first nine months.
But by age two they were virtually no more likely than others to have had accidents or injuries.
Social Development Ministry national children's director Sue Mackwell said the ministry still planned a trial of "predictive risk modelling" based on its own set of risk factors.
"Decisions will be made by the Vulnerable Children's Board on the final technical form of the trial model, arrangements for the maintenance and updating of the model, and how the model should be trialled and evaluated."
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