Fertility treatment is more effective in New Zealand than in Australia, say researchers who believe this may be because of Government rationing of the service here.
This tight rationing may have produced a "healthier" population of women seeking the treatment.
About half of in-vitro fertilisation (IVF) treatment cycles are state-funded
in New Zealand and access is strictly rationed. By contrast in Australia there is virtually no restriction on access to government funding, although couples have to pay about 6 per cent of the total cost of their treatment.
A fertility treatment study led by Professor Cindy Farquhar, who is associated with the Auckland District Health Board's Fertility Plus clinic, found the rates of pregnancy and live birth were higher in New Zealand.
For women younger than 35, the pregnancy rate was 37.5 per cent in New Zealand and 31.2 per cent in Australia, according to the study by Professor Farquhar and colleagues at the University of New South Wales.
The criteria for access to public funding in New Zealand include the woman being less than 40 years old, of body mass index less than 32, and being a non-smoker. The couple must score at least 65 per cent on clinical and social factors. The state pays for a maximum of two cycles.
"The results from our analysis could be attributed to restrictions in funding, which have resulted in a highly selected, potentially healthier population of women undertaking ART [assisted reproductive technology] in New Zealand," the researchers say in a paper published in the European journal Human Reproduction.
Because about half of cycles in New Zealand occur only after the couples go through the scoring system, at least half of women undergoing the treatment are "highly selected for BMI, age, non-smoking status and low likelihood of conceiving spontaneously. In Australia there are no selection criteria".
"If the criteria are being implemented, then the New Zealand women are likely to be on average thinner and to smoke less.
"Women who smoke take twice as long to conceive with ART, than do women who do not smoke, and women who have higher BMIs are also more likely to have poorer outcomes in terms of miscarriage and pregnancy outcomes and to have higher cycle costs."
