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Western lifestyle increases the risk of premature birth

The westernisation of Asian societies will see its pre-term birth rate boom, predicts an Australian researcher at the forefront of advising China about how to manage this trend. Linda Belardi reports.

Women living in Western Australia are almost three times more likely to give birth to preterm babies compared to women in China, according to a joint study by researchers in WA and China.

The study, led by Winthrop Professor John Newnham, from the University of Western Australia, found that the rate of preterm birth increased as women moved to a more Western environment.

Chinese women record one of the lowest rates of preterm birth in the world, significantly lower than women in Hong Kong or Western Australia.

Newnham said the findings suggested that preterm birth rate is strongly linked to environment and lifestyle.

The moment Chinese women living in WA no longer required an interpreter, their pre-term birth rate doubled. "If the Chinese women needed an interpreter their pre-term birth rate was 2.5 per cent and the moment they didn't need an interpreter the birth rate doubled," Newnham told Nursing Review.

It is believed the phenomenon of low pre-term birth rates also extends to women from other Asian countries, such as Korea and Japan.

The WA study has been corroborated with NSW data, which also linked low preterm birth to Asian societies.

As China continues on its path of economic and social reform, it may pay the price in a rising pre-term birth rate, he said. "I expect China is going to have a lot more pre-term births as they become more westernised."

The results of this study may help with the prevention of preterm birth by studying populations that have low rates rather than focusing on those with the highest rates, he said.

"We've had so much work and expenditure on neo-natal intensive care that I think avenues to prevent preterm births are really welcomed by professionals," he said.

The most significant factors associated with preterm birth rate were smoking, age and sex during pregnancy.

The smoking rate in China amongst women of reproductive age is extremely low, approximately 0.1 - 0.2 per cent in Nanjing, compared with 17 per cent of women in Western Australia.
China's one-child policy has also actually positively contributed to China's low pre-term birth rate.

Extremes of age for childbirth such as teenage and mature-age pregnancy - which are very common in Western society - are extremely rare in China. This is in large part, a behavioural response to China's one-child only policy, which has encouraged Chinese women to reproduce in the ideal age-range.

Chinese women are also more likely to avoid becoming pregnant if they are sick and IVF procedures are rare, said Newnham.

The expanding number of women being assisted to become pregnant may be contributing to higher rates of pre-term births.

"Modern medicine is progressively making our reproductive population 'sicker'. We are now delivering women who have been operated on for congenital heart disease. Women with diabetes who would never have become pregnant in previous generations are now pregnant. Women who are completely infertile are getting pregnant through a variety of IVF procedures. The 'reproductive fitness' of women in the Western world is probably deteriorating."

Sex in pregnancy may also be a contributing factor.

"Among Chinese women, sexual activity appears to be infrequent." Sexual activity among pregnant Chinese women in Hong Kong was reduced by more than 90 per cent, while it was reported to continue during pregnancy in 86-100 per cent of couples in non-Chinese populations.

"Any role for sexual activity in causing preterm birth remains controversial and unproven, but it most certainly presents an area warranting further investigation," he said.

While further research is needed to dissect these variables, Newnham said it appears that the behaviour of women plays a huge role in pre-term birth.

"The behaviour of obstetricians is not causing pre-term births, it's something about the women themselves," he said.

This study has also opened up a new field of opportunities in pre-term birth prevention. "Learning how to prevent pre-term birth needs to be one of the highest priorities for health professionals," he said.

The effect of the environment on China's pre-term births will be seen in Chinese women at a population level as the country undergoes rapid economic and social change, but also as part of Chinese immigration to Western societies.

Researchers in Perth, Hong Kong and Nanjing examined records of 26,611 pregnancies in China's rural Jiangsu Province, 48,976 pregnancies in Hong Kong and 185,798 pregnancies in Western Australia.

In Jiangsu Province, one of the largest provinces in China with a population of 77 million, just 2.6 per cent births were recorded as preterm in urban areas and 2.9 per cent in rural parts.
The rate of preterm birth among non-resident Chinese women in Hong Kong was 5.6 per cent and 7.6 per cent for Hong Kong residents.

In Western Australia, the rate of preterm birth was significantly lower in Chinese women who were born in China (4.4 per cent) compared with the general rate for women in WA of 8.2 per cent.
It took Newnham five years to record China's pre-term rate, a task that had not been previously undertaken by either the Chinese government or the country's health professionals.

In the study, published in the Australian and New Zealand Journal of Obstetrics and Gynaecology, preterm birth was defined as birth after 24 completed weeks and before 37 completed weeks of gestation.

The research, which has attracted interest from the Chinese government, will continue to investigate why its pre-term birth rate is so low.

"We are trying to give them a glimpse of their future. The Chinese government has opened the doors for all collaboration, which is a significant opportunity. This sort of research is very good for international relationships."

International comparison of pre-term birth rates: USA - 12-13 per cent, AUS - 7.2 per cent, CHINA - 2.6 per cent and HONG KONG - 7.6 per cent.

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