Road pollution link to low birth weight

LIVING near a busy road may increase a pregnant woman’s chances of having a small baby, new research suggests.

Scientists in the US found a significant link between traffic pollution and reduced birth weight.

Two kinds of pollution produced by motor vehicles — tiny sooty particles and nitrogen dioxide — were found to have an impact.

The effects were much more pronounced for women with pregnancy complications.

Researchers looked at data on almost 336,000 babies born in New Jersey between 1999 and 2003.

Air quality measurements from within 9km of the mothers’ homes were used to calculate levels of pollution exposure during each three-month period of pregnancy.

Pollution was linked to reduced foetal growth even after taking into account mothers’ risk factors such as age, poor education, ethnicity, poverty, smoking and being a single parent.

One of the harmful pollutants was PM 2.5 particulate matter — tiny specks of sooty chemicals measuring 2.5 micrometres or less in diameter.

Particulate matter is produced from vehicle exhausts and can lodge in the lungs. Fine particles, such as PM 2.5s, which penetrate deep into the lungs, have been linked to deaths from heart and respiratory diseases.

The study found that in the first and third trimesters of pregnancy, the likelihood of having a “small for gestational age” (SGA) baby rose significantly with higher PM 2.5 levels.

The risk went up by more than 4% for every PM 2.5 increase of four micrograms per cubic metre of air.

A similar association was seen between nitrogen dioxide concentrations and very small birth weight babies. At all stages of pregnancy, the risk of having a “very small for gestational age” (VSGA) baby increased by more than 7% with each 10 parts per billion increase in nitrogen dioxide.

SGA babies were defined as being between 75% and 85% of normal size. VSGA babies were at least 75% smaller than normal.

For women with pregnancy complications such as separation of the placenta before birth, the small baby risk was heightened up to five-fold.


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