Proximity to highways affects newborns’ health: study
Reported July 30, 2008
MONTREAL – Wealthy pregnant women living near highways on the island of Montreal are more likely to deliver pre-term, low weight or small babies, researchers say.
The odds of delivering a low-weight infant are 81 per cent higher for expectant mothers living in affluent neighbourhoods within 200 metres of highways, according to a report published in the August edition of the Journal of Epidemiology and Community Heath. Women in the same category are 58 per cent more likely to deliver early compared to women who don’t live near an expressway.
“At the beginning, we thought that low-income mothers would be more susceptible to pollution from highways, so we were quite surprised,” said Dr. Mélissa Généreux, lead author of the study. Généreux is a public health resident at the Université de Montréal-affiliated Maisonneuve-Rosemount Hospital, and she has a hypothesis to explain the unexpected results.
“Low-income mothers and mothers from low-income neighbourhoods are often exposed to other risk factors during their pregnancies,” said Généreux, explaining that such women are more likely to smoke, to have poor nutrition, be exposed to domestic violence or have less access to pre-natal care.
“More affluent mothers are relatively protected from these risk factors, so they might be more affected by…pollution from highways.”
Among all births studied, women who lived within 200 metres of highways faced 17 per cent higher odds of low-weight births and a 14 per cent increased risk of preterm delivery.
The researchers examined data on close to 100,000 live births recorded from 1997 to 2001 in the Quebec birth registry, which also includes mothers’ education levels. They compared those records to 2001 Census data on the proportion of residents below the low-income threshold to determine the socioeconomic status of each neighbourhood and individual.
Highways referred to in the study were identified as major roadways with posted speed limits of at least 70 kilometers per hour, and exposure to highway pollution was determined by previous studies.
The study is the first to consider the relationship between proximity to highway pollution, individual and neighbourhood socioeconomic status, and newborn health. Previous research conducted in Taiwan found a correlation between exposure to pollution and adverse birth outcomes, while studies in Los Angeles, California, link high traffic density with increased low-weight and pre-term births among poor women.
The contradiction between the findings likely relates to the availability of health-care for poor people in the U.S. compared to Canada, Généreux said.
Exposure to pollution during pregnancy may impair fetus growth as toxins may be absorbed and exchanged through the placenta. Pollution has also been shown to increase maternal susceptibility to infection and respiratory problems.
The study, titled “Neighbourhood socioeconomic status, maternal education and adverse birth outcomes among mothers living near highways,” was a joint project between the Université de Montréal and the University of South Australia.
Source : The Gazette