Higher premature birth risks linked to vehicle emissions exposure

Residential exposure measured

Wendy Natt, Jul 02, 09.

Pregnant women living close to major roadways with heavy traffic congestion are more likely to suffer serious pregnancy complications, including preterm birth and preeclampsia, according to a recent study by researchers at the University of California, Irvine. The study population consisted of pregnant mother and babies living in the South Coast Air Basin of Southern California and within 1.9 miles of a major highway. Researchers found a positive correlation between the likelihood of these adverse effects and increased exposure to certain toxins in vehicle emissions.

Hospital records for babies born near the Ports of Los Angeles and Long Beach, and in adjacent Orange County - areas heavily trafficked by commuters as well as trucks transporting port cargo - provided birth data for the study population. Levels of residential exposure to local traffic-generated air pollution were determined by comparing a mother’s residence during pregnancy and at the time of birth with local traffic data sources and geographic dispersion models for concentrations of nitrous oxides and particulate matter, toxins present in vehicle emissions.

Researchers noted a 33% increase in the risk of preeclampsia, a condition that includes heightened blood pressure that can lead to premature birth, for women who spent the duration of their pregnancies living in areas with the highest exposure, while a 128% increase in the risk of very preterm birth (babies born before the 30th week of gestation) was noted for mothers with the same levels of exposure to vehicle emissions. The incidence of moderately preterm and preterm births also increased in a linear fashion with greater exposure to emissions, but to a lesser extent.

The report makes this statement about the implications the study’s findings for the health effects of future growth and traffic congestion in the region:

Due to population and economic growth and the lack of effective public transportation in the Los Angeles area, the amount of passenger traffic and of goods being moved through this region is projected to increase substantially in the next decade… Such rapid growth in traffic-related fossil fuel use is expected to occur worldwide…, adding urgency to research evaluating the impact of increased vehicle emissions on reproductive health outcomes.

The report’s authors note that this is the first study to show a correlation between exposure to local traffic-generated pollutants at the birth residence and the development of preeclampsia during pregnancy. It also provides new data that lends support to earlier studies showing the effects of traffic-borne emissions exposure on preterm births.

A Scientific American article also reported on the study.