Pollution linked to low birth weight

Traffic pollution could harm babies while they are still developing in the womb, new research has warned. The more road pollution a mother is exposed to in early and late pregnancy, the more likely it is that her baby would not grow properly, a US study found. But UK experts stressed that much more detailed research into a link was needed.

The researchers, from the University of Medicine and Dentistry in New Jersey, looked at 336,000 babies born in New Jersey between 1999 and 2003, checking birth certificates and hospital discharge records. They recorded details including each mother's ethnicity, marital status, education, whether or not she was a smoker - as well as where she lived when her baby was born. Daily readings of air pollution from monitoring points around the state of New Jersey were taken from the US Environmental Protection Agency. The scientists then took data from the monitoring point within six miles (10 km) of the mothers' homes to work out what their exposure to air pollution had been during each of the three trimesters of pregnancy. Mothers of small, and very small, birth weight babies were more likely to be younger, less well educated, of African-American ethnicity, smokers, poorer, and single parents than mothers with normal birth weight babies. But, even after these factors had been taken into account, higher levels of air pollutants were linked to poor foetal growth.

Two kinds of pollution produced by cars tiny sooty particles and nitrogen dioxide - were found to have an impact, according to the study, published in the Journal of Epidemiology and Community Health."Our findings suggest that air pollution, perhaps specifically traffic emissions during early and late pregnancy and/or factors associated with residence near a roadway during pregnancy, may affect foetal growth," said Professor David Rich.

It is still not clear exactly how air pollution might restrict foetal growth. But the study said previous research suggests that air pollution might alter cell activity, or cut the amount of oxygen and nutrients a baby receives while in the womb. Professor Patrick O'Brien, of the UK's Royal College of Obstetricians and Gynaecologists, told the BBC: "This is an interesting study because it flags up a possibility of a link. "But I think it needs to be looked at again in more detail because of the probability of confounding factors.”