Highway Proximity Linked to Birth Weight

A Canadian study suggests that mothers living near highways are more likely to give birth to preterm or low-birth-weight babies, but contrary to previous studies it found the association only in wealthy neighborhoods.

The study, published in the August edition of the Journal of Epidemiology and Community Health, looked at the medical records of 99,819 singleton births in Montreal from 1997 to 2001. Researchers measured the distance of mothers' addresses from the nearest highway and determined their socioeconomic and education levels from census data.

They found that compared with living in a wealthy neighborhood farther away, living in a wealthy neighborhood within 220 yards of a highway was associated with a 58 percent increased risk of preterm birth, an 81 percent increased risk of low birth weight, and a 32 percent increased risk of being small for gestational age. Proximity to a highway was not associated with any adverse birth effects in poorer neighborhoods.

"Low-income mothers are exposed to more risk factors - smoking, poor nutrition, poor access to prenatal care, domestic violence," said Dr. Mélissa Généreux, the lead author and a resident physician at the University of Montreal. "More advantaged mothers are protected from these risk factors, so they might be more affected by the addition of a single new risk factor, pollution from highways."