6th December 2017 – The health of unborn babies is being put at risk by traffic pollution. That's according to a large study into more than 540,000 full-term births in the Greater London area.
It's found that pollution from road traffic is associated with babies being born with a low birth weight - less than 2500g (2.5kg or 5.5lbs) – which can have lifelong implications for health.
The researchers believe their findings apply to other UK and European cities and are calling for improvements in air quality in urban areas.
Dr Patrick O'Brien, spokesperson for the Royal College of Obstetricians and Gynaecologists (RCOG) told in an emailed statement: "The results from this large study add to a growing body of evidence on the association between air pollution from road traffic and its adverse impact on babies' health, even before they are born. It should place renewed pressure on Governments to adopt meaningful environmental health policies to reduce air pollution and give babies a healthier start in life."
Some babies are just smaller than others but being a low weight at birth increases the chances of a baby getting diseases which could affect their hearing or eyesight. They also have a greater risk of sudden infant death syndrome (SIDS or cot death), asthma, learning difficulties, and cerebral palsy.
Low birth weight babies are also weaker and find it harder to keep warm.
Traffic pollution study
For the new study a team of London researchers led by Imperial College London looked at whether there was a link between babies born with a low birth weight or born small for their gestational age, and air, and noise, road traffic pollution.
The babies were all born between 2006 and 2010. The mother’s all lived within the area of the M25. Their home address was noted and average monthly concentrations of traffic related pollutants were estimated along with average day and night-time traffic noise levels.
The researchers found that increases in traffic-related air pollutants - especially fine particles from exhausts and brakes or tyre wear (PM2.5) - were associated with 2% to 6% increased odds of having a low birth weight baby and 1% to 3% increased odds of having a baby small for its gestational age.
However, they found that traffic related noise pollution appeared to have no effect on birth weight.
The findings have been published in the BMJ (British Medical Journal).
Air quality concerns
The study authors estimate that reducing annual PM2.5 pollution in London by 10% would prevent approximately 90 full term babies (3%) being born with a low birth weight each year in the capital.
In a linked editorial article, researchers at the University of Edinburgh say coordinated action can make a difference and point to Beijing, where air quality levels were improved during the 2008 Olympics.
They say changing behaviour, for example not walking alongside major roads, is unlikely to result in substantially different long-term exposures to traffic pollution and women are, therefore, reliant on policy change to reduce the risk to their unborn baby from air pollution.
Dr O'Brien from RCOG says: "Exposure to some level of air pollution is unavoidable in day-to-day life. Even though we need more research to be more certain about the effects of air pollution on foetal development, we would recommend that where possible that pregnant women should reduce their exposure to air pollution and make lifestyle changes, such as quitting smoking."
BMJ: Press release
Impact of London’s road traffic air and noise pollution on birth weight: retrospective population based cohort study
Royal College of Obstetricians and Gynaecologists (RCOG):
Royal College of Physicians: Every breath we take: the lifelong impact of air pollution
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