‘Pollution threat’ to mums-to-be: One in every 20 cases of pre-eclampsia blamed on higher levels of air pollutionPre-eclampsia can threaten the life of both mother and babyPollution could be a factor in up to 2,000 cases every year in the UK
00:06 GMT, 7 February 2013
08:07 GMT, 7 February 2013
Threat: Air pollution to trigger potentially fatal pre-eclampsia in expectant mothers, a study has found
Exposure to air pollution could trigger potentially fatal pre-eclampsia in pregnant women, researchers have warned.
Women with asthma are particularly
vulnerable to the condition – marked by high blood pressure and fluid
retention – according to a new study.
It blamed one in every 20 cases of pre-eclampsia on higher levels of ozone pollution in the air during the first three months of pregnancy, as well
as an increase in premature births.
The rate would mean pollution was a factor in up to 2,000 cases of pre-eclampsia in the UK each year.
As many as one in 20 first-time mothers develop pre-eclampsia, while
around 20 women die each year from conditions linked to high blood
pressure. It is thought to claim the lives of 600 babies a year.
The only treatment is to deliver the baby early with an emergency Caesarean.
The new study adds to evidence of a link between air pollution and
premature birth, with international research earlier this week showing
higher pollution levels raised the risk of low birth weight.
The study looked at almost 121,000 births in Greater Stockholm, Sweden, between 1998 and 2006.
It compared the records with national data on the prevalence of asthma
among the children’s mothers; and levels of the air pollutants ozone and
vehicle exhaust (nitrogen oxide) in the Stockholm area.
In all, 4.4 per cent of the pregnancies resulted in a premature birth
and the prevalence of pre-eclampsia was 2.7 per cent, say findings
published in the online journal BMJ Open.
There was no association between exposure to levels of vehicle exhaust
and complications of pregnancy, nor were any links found for any air
pollutants and babies that were underweight at birth.
But there did seem to be a link between exposure to ozone levels during
the first three months of pregnancy and the risk of premature birth
before 37 weeks and pre-eclampsia.
Each rose by four per cent for every 10 microgram per cubic metre
increase in ambient ozone during this period, says the analysis.
Mothers with asthma were 25 per cent more likely to have a child born
prematurely and 10 per cent more likely to have pre-eclampsia than mums
without this condition.
Vulnerable: Pregnant women with asthma were 10 per cent more likely to have pre-eclampsia than those without the condition
The effect of pollution on inflammation processes in the body may be a potential mechanism, say the Swedish researchers.
Asthma is an inflammatory condition and ozone may therefore have
worsened respiratory symptoms and systemic inflammation, so accounting
for the larger increase in the risk of premature birth among the mums
with asthma, suggest the researchers.
After taking account of various factors, they calculated that one in
every 20 (five per cent) cases of pre-eclampsia were linked to ozone
levels during early pregnancy.
Lead researcher David Olsson, of the department of public health and
clinical medicine at Umea University, said the findings should lead to
improved monitoring of women with asthma during pregnancy.
He said ‘It’s difficult to put into practice measures that will
effectively reduce the risk, but it shows the importance of ensuring
women’s asthma symptoms are under control during early pregnancy. They
need to use their medication to help counteract the possible health
effects of pollution.
‘The study increases the evidence suggesting we should strive to keep
reducing pollution levels to improve human health’ he added.