Older mothers go forth and multiply

By REBECCA WALSH

More twins are being born in New Zealand than ever as women delay childbirth and use fertility treatments to help get pregnant.

Last year there were 885 multiple births out of 54,916 births. That included a record 874 sets of twins and 11 sets of triplets (or higher order births).Between 1980 and 2000 the number of multiple births increased 74 per cent, growing rapidly in the past five years.

At the same time, the rate of multiple pregnancies increased from 1 per cent of all births to 1.6 per cent.

Mansoor Khawaja, chief demographer for Statistics NZ, said international research pointed to delayed childbirth and growing use of fertility-enhancing drugs for the increase.

It also showed variations across countries. Although seven out of 1000 births in Japan were multiple, in African countries such as Zimbabwe and Nigeria the figure was more than 20 out of 1000.

In New Zealand the median age of women having children is 29.9 years compared with 25.7 in 1980.

Women aged 30 and over accounted for a quarter of all multiple births in 1980 compared with three-fifths last year.

Research here shows women aged 35-39 are more than twice as likely as a teenager to have a multiple birth.

Dr Richard Fisher, director of Auckland-based Fertility Associates, said this was probably because older women's ovaries were working harder to produce an egg and sometimes more than one would "sneak out".

Although fertility treatments played a significant role in the increase in multiple births, the greater number occurred naturally, he said.

IVF and ovulation-induced pregnancies (through hormone injections or tablets) accounted for about 1 per cent of the total number of births in New Zealand.

About 25 per cent of IVF pregnancies resulted in twins.

"If you ask anyone who has twins, what's the first thing people say to them? It's 'you must have had IVF'. The reality is, three times more will have conceived spontaneously than will have conceived with IVF."

Fertility specialists were working to reduce the chances of multiple pregnancies to minimise the risk to mother and child. For the past couple of years only two embryos had been replaced in women under 38, compared with the three or four of previous years.

"The drive now in IVF is to putting single embryos back."

He said this reduced the chance of getting pregnant.

Sue Mulrennan, of Hillsborough, was 34 when she had twins Eleanor and Victoria, who have just started school.

She did not have fertility treatment and there was no history of twins in the family, but her brother and a sister have since had twins.

She said that despite all the negative publicity and literature surrounding multiple births, having twins was "magic".

"The first thing you notice is that they are far more content because they always have a buddy ... As someone said, being a twin means there's always someone for the other end of the see-saw."

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