January 16, 2017 1049 GMT
Pre-eclampsia — a condition suffered by 42,000 pregnant women in Britain each year — is made more likely by noise and pollution from roads, according to a large study, dailymail.co.uk wrote.
Researchers believe the toxins from vehicles and sound of traffic from nearby roads may increase stress levels and cause inflammation that leads to rising blood pressure associated with the condition.
The Danish study of 73,000 women — the first to establish a link between traffic and pre-eclampsia — adds to growing concerns about the health impact of air and noise pollution.
Earlier this week a separate study published in the Lancet medical journal warned people who live near roads are also at significantly higher risk of developing dementia.
Those concerns add to established evidence that traffic fumes increase the risk of heart disease and asthma.
The UK’s National Health Service (NHS) watchdog National Institute for Health and Care Excellence (NICE) last month called for urgent action to tackle the problem, warning that air pollution contributes towards 25,000 deaths a year in England — almost five percent of all deaths.
Despite overwhelming evidence of health impacts, the UK has struggled to control air pollution, with 37 cities across Britain persistently breaching legal limits of air toxins set by the EU.
Pre-eclampsia affects around 6 percent of pregnancies in the UK — and in severe cases can lead to stillbirth or maternal death.
The new results may help to explain why until recently rates of pre-eclampsia have been increasing in many countries.
It could also provide some clues about the underlying causes of pre-eclampsia.
Researchers found that for every 10-decibel increase in noise from traffic — roughly a doubling in audible volume — there was a 10 percent increase in the risk of pre-eclampsia and high blood pressure problems in pregnant women.
Similarly, for every 0.01 micrograms of nitric dioxide from car exhausts in a liter of air — a tiny increase — the risk of the condition rose by seven percent.
“Study leader Professor Marie Pedersen, of the University of Copenhagen, said: ‘The rise in risk we saw is significant in terms of impact on a population level, as a 10-unit increase in pollution and noise is very small.”
Pre-eclampsia usually occurs in the second half of pregnancy and can lead to problems with the flow of blood through the placenta.
Warning signs include high blood pressure, swelling in their feet, face and hands, severe headaches, vision problems and pain below the ribs.
As the delivery of nutrients can be hampered by the problems with the placenta, it can restrict the growth of the unborn baby.
There is currently no cure for the condition and often babies need to be delivered early to prevent it from worsening.
Pre-eclampsia and hypertensive disorders are among the leading causes of maternal death and stillbirth.
Around 500 babies are thought to die in the UK each year as a result of the condition.
Those at the highest risk include women who are obese, have high blood pressure before they are pregnant, those suffer from diabetes or have a family history of pre-eclampsia.
Professor Pedersen said her study shines new light on the root causes of the condition, which has been poorly understand in the past.
She said: “Air pollution causes inflammation and oxidative stress, which has been linked to damage to blood vessels, immune system changes and elevated blood pressure.
“Noise may induce stress and disturb sleep, which has also been associated with similar changes.
“We observed the strongest effects for mild pre-eclampsia and early-onset of pre-eclamsia.”