High air pollution exposure increases risk of premature birth

Mothers-to-be, take note! Exposure to high levels of small particle air pollution is associated with an increased risk of premature birth, a new study has found.
Researchers at the US Cincinnati Children's Hospital Medical Centre and the University of Cincinnati, identified a 19 per cent increased risk, with the greatest risk when exposed to air pollution during the third trimester of pregnancy.
Diesel exhaust particles make up a substantial portion of particulate matter in urban areas and smaller particles have greater potential to be inhaled into the lungs and can cause serious health problems, including several heart and pulmonary diseases, the study found.

"Although the risk increase is modest, the potential impact is robust, as all pregnant women are potentially at risk," said Emily DeFranco, an associate professor at the University of Cincinnati.
"We estimate that decreasing the amount of particulate matter in the air below the US Environmental Protection Agency's (EPA) standard threshold could decrease preterm birth in women exposed to high levels of small particulates by about 17 per cent, which corresponds to a 2.22 per cent decrease in the preterm birth rate in the population as a whole," said DeFranco.
The researchers studied birth records in Ohio between 2007 and 2010. The population included nearly 225,000 singleton (not multiples) live births.

Of these, more than 19,000 births were preterm, that is birth before 37 weeks of pregnancy. The birth records were linked to average daily measures of fine particulate matter of 2.5 microns or less in width.

These measures were recorded by 57 EPA network air monitoring stations across the state.
The vast majority of births, 97 per cent, occurred in highly urbanised areas, where most monitoring stations are located and exposure levels were likely to be highest.
Preterm birth rates were higher among mothers exposed to high levels of airborne particle pollution above the EPA standard, as well as among mothers of 40 or older, black mothers, and women with no prenatal care or with lower education level.

The study was published in the journal of Environmental Health.