Now pregnant women are being advised to take into account their home's location when compiling a list of pregnancy worries. An Australian study found that pregnant women have a higher risk of giving birth prematurely if they live near a concentration of busy roads and highways. "The most striking result was the reduction in gestation time of 4.4 per cent or almost two weeks associated with an increase in freeways within 400 metres of the women's home," said Professor Adrian Barnett, the study's author. He believes both air and noise pollution could be contributing factors.