NZ study will keep tabs on 7000 children

Carolyn Moynihan
29 Nov 2010
Reproduced with Permission

The first results from a New Zealand cohort study were published over the weekend with great fanfare, the first NZ Herald headline reading, "40pc of pregnancies unplanned". I think we were meant to be shocked rather than delighted at the lack of calculation behind so many births.

One reason for that soon became apparent.

The finding that 40 per cent of births are unplanned has huge implications because unborn babies may be harmed by the mother's drinking, eating and smoking before she realises she is pregnant.

Almost a third (31 per cent) of the women who fell pregnant by accident drank alcohol during the first three months of their pregnancy, compared with only 17 per cent of the women whose babies were planned.

"We will be able to track how those patterns of drinking before and during pregnancy are reflected in birth outcomes and early development," said study director Dr Susan Morton of Auckland University.

"That is novel internationally."

The study, Growing Up in New Zealand, is the first of its kind in the country since the Dunedin Multidisciplinary Health and Development Study began in 1972. That study, which has followed 1037 babies since their birth in 1972-73 in the southern city and is still going, has become internationally famous. The new study, which began a couple of years ago, is following 6822 children from birth to age 21. They are from the country's northern cities of Auckland and Hamilton.

The population of the new study is much more ethnically diverse. Almost half the babies in the new study have multiple ethnicities and more than a third of the mothers were born overseas -- most in Asia. However, Europeans and Maoris are still dominant in the mix.

The study aims to find the factors that help some children do better in life than others. One figure with predictive power might be this: 6822 mothers came up with 4404 partners' contact details. And of these (at the time of enrolment in the study, presumably) 63 per cent of the mothers were married or in a "civil union", 28 per cent were cohabiting, 4 per cent were "dating" and 5 per cent had no relationship with the father.

By contrast, 95 per cent of the Dunedin parents were legally married. Considering that a further 5 per cent in the current study separated or moved out of the same house during pregnancy study leader Susan Morton is "wary":

"Over time we expect there will be a lot more change in family structure."

Another big difference: the Dunedin mothers had an average number of 2.9 children; the Auckland-Waikato group have just 2.0 -- even though they have nearly the same average age: 30 compared with 29. (The median age of mothers giving birth in 1972 was just under 25, so the Dunedin group were comparatively "older" mothers, in keeping with their larger tally of children.)

And one more thing: only 23 per cent of Dunedin mothers were in paid work by the time the child in the study was aged 3, but 89 per cent of today's group of mothers plans to return to work -- on average after 14-15 months.

However, one thing has apparently changed for the better: in 1972 only 55 per cent of the mothers had breastfed their baby by age 3; 97 per cent of today's group planned to breastfeed.

This will be a study to watch.