BRISBANE, Australia - Women who live near freeways and highways are more likely to give birth prematurely, said an Australian new research released on Monday.

The study of 970 mothers and their newborn babies in Logan City, south of Brisbane, led by Associate Professor Adrian Barnett, from the Queensland University of Technology's Institute of Health and Biomedical Innovation, has revealed the link between the concentration of major roads around a woman's home and early birth.

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"The most striking result was the reduction in gestation time of 4.4 percent - or almost two weeks - associated with an increase in freeways within 400 meters of the women's home," said Barnett.

The study counted the number of roads around the mothers' homes up to a 500-meter radius.

"We examined the distance between the home and busy roads to find the distance at which most of the negative effects on birth outcomes occurred because this has implications for local governments planning expansions or new roads," he said.

Most of the effects were within a 200-meter radius but negative health effects were present up to 400 meters.

Barnett said the study had also taken into account the effects of smoking levels and the socio-economic status of the mothers.

He said the effects of noise pollution were considered to be a possible contributing factor though it was difficult to separate the effects of air and noise pollution.

"Vehicles braking and starting means that road junctions have some of the highest levels of noise and air pollution," he said, adding "disturbed sleep during pregnancy may cause extra stress and be a risk factor for adverse birth outcomes."

Barnett also said the study pointed to the fact that pregnant women should reduce their exposure to traffic.