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© corbis
Heavy intake of air pollutants from car exhausts could lead to an increased risk of developing high blood pressure disorders during pregnancy, according to a recent study
Polluted cities may be more harmful to pregnant women than smoking cigarettes.

This is the claim of a recent U.S. study which argues that mothers-to-be are at a high risk of developing complications from exposure to car exhausts and industrial waste.

Heavy intake of air pollutants could lead to an increased risk of developing high blood pressure disorders during pregnancy, according to the study.

Scientists at the University of Florida said the worst offending pollutants include two specific types of particulate matter; carbon monoxide and sulphur dioxide.

Sulphur dioxide is emitted from power plants and industries, while most carbon monoxide is produced by car exhaust.

'Fetal development is very sensitive to environmental factors,' said Dr Xiaohui Xu, an assistant professor of epidemiology in the colleges of Public Health and Health Professions and Medicine.

'That is why we wanted to do this research. Hypertension (high blood pressure), in particular, is associated with increased morbidity and mortality, causing a lot of problems for the mother and fetus, including pre-term delivery.'
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Air pollution can lead to high blood pressure which currently affects 10 per cent of pregnant women
Hypertensive disorders are thought to affect about 10 per cent of pregnancies.

Despite the serious risks to mother and baby, little is known about what specifically causes these conditions to develop in pregnant women, the researchers say.

To gain a better understanding, the researchers examined data from women who gave birth in Jacksonville, Florida, between 2004 and 2005 and environmental data from their communities.

The sample included more than 22,000 pregnant women.

The researchers gauged how much pollution the women were exposed to throughout their pregnancies to measure the levels of several pollutants.

Among the sample of women, 4.7 per cent developed a hypertensive disorder during pregnancy.

Exposure to air pollutants throughout the first two trimesters of pregnancy increased women's risk of developing one of these conditions, Dr Xu said.

They determined this after controlling other factors that could affect a woman's risk for developing hypertension, such as socioeconomic status, exposure to co-pollutants and smoking during pregnancy.
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© Ian Hooton
The researchers claim polluted cities may be more harmful to pregnant women than smoking cigarettes
But scientists said they could not determine conclusively whether exposure early in the pregnancy or late in the pregnancy was more likely to increase a woman's risk for hypertension.

'It looks like the whole period has impacts for hypertension,' he said.

On the basis of these findings, the researchers say more air pollution control is necessary to prevent dangerous complications in pregnant women and babies.

The researchers now plan to expand their study throughout the state and also examine other conditions that could be affected by pollution.

'We are trying to look at several outcomes,' Dr Xu said.

'We also want to look at preterm delivery and low birth-weight and find out what the effects of breathing contaminated air are on fetal development.'