KEY POINTS:
The age of delayed motherhood seems to have settled at its "logical" - and biological - upper limit, according to Statistics New Zealand.
Recording a 44-year high in births last year, the state agency has found the median age of women giving birth has stabilised at just over 30. It has been rising since 1972, when a rapid change to later marriage and delayed child-bearing began to lift the median age of motherhood from 25.
The median settled at 30.1 last year, having dropped fractionally in the previous two years. The median is the point where half are older and half are younger.
"Logically there is a limit as to how old mothers can get," Statistics New Zealand senior demographer Bill Boddington said yesterday.
Fertility Associates Auckland scientific director Dr Bert Stewart said 46 was the oldest at which a woman had become pregnant after fertility treatment in New Zealand.
Techniques to freeze eggs and thaw them later for implantation - not yet fully approved in New Zealand - are still being refined but will have little effect on general fertility because of the high cost: probably $25,000 for a chance of having a family.
The latest figures also show that a girl born now can expect to live to 81.9, in excess of 10 years more than the life expectancy at birth of one born in the early 1950s.
Statistics New Zealand said 64,040 births were registered last year - the most since 1963, the tail-end of the post-war baby boom.
That pushed the birth rate to 2.2 births a woman last year, a level of fertility last reached in 1990. But while this is technically above the rate of 2.1 required to replace the current population without migration, it would need to be sustained for a number of years to achieve replacement. It may be just a short-lived increase, as it was around 1990, although when coupled with health-worker scarcity it has been enough to put severe pressure on some maternity and newborn units.
In Counties Manukau, where Middlemore Hospital's shortage of midwives has been dubbed a "timebomb", births have increased by 25 per cent in six years.
But while the birth rate was up, Mr Boddington said it fell far short of the rate in the 1960s boom years.
"If you had 1963 fertility rates in the latest year, then rather than 64,000 births, we would have had almost 120,000 births. That puts it in a historical perspective."
The underlying reasons for last year's increase were unknown. But the rising birth rate reflected a trend among developed nations.
Mr Boddington said it was tempting in countries like New Zealand, France and Australia which had introduced "pro-natal policies" - such as expanding paid parental leave in New Zealand - to think these accounted for increasing birth rates.
But other countries that had not introduced such schemes, and others that had had them for many years, had also experienced "some increase" in their birth rates.
The total fertility rate last year for Maori women, at 2.94 births a woman, remained well above the rate for the whole population. By age, the highest fertility rate last year was among women aged 30-34, while in 1967 it was among those aged 20-24.
The fertility rate for women aged 40-44 increased by more than half in the decade to last year.
WE'RE LIVING LONGER TOO
Life expectancy in New Zealand continues to increase, with girls born today likely to live to the age of 81.9 years and boys to 77.9.
Figures released by Statistics New Zealand showed that a man aged 40 today could expect to live to 79.8 and a woman to 83.1.
And the older a person is today, the older they are likely to be when they die, as factors such as deaths from accidents or lifestyle choices are removed. An 80-year-old man today is statistically likely to live to 88.1, and an 80-year-old woman to 89.5.
The greatest rise from 50 years ago is in the life expectancy of babies and young people. In 1950-52, a baby boy's life expectancy was 67.2 and a baby girl's 71.3.
