Air pollution from vehicles increases the risk of dangerously high blood pressure in pregnant women, US government researchers report.
Scientists from the US National Institute of Environmental Health Sciences' (NIEHS) National Toxicology Program analysed published studies on the links between traffic-related air pollution and preeclampsia. The analysis was reviewed by experts from academia and industry, who agreed unanimously with the final conclusion of the report, released om 18 December.
High levels of traffic
"What we found when we reviewed the literature is that exposure to PM2.5 [fine particulate matter] from traffic emissions was associated with development of hypertensive disorders in pregnant women," said researcher Brandy Beverly, lead scientist at NIEHS.
"When these women are exposed to PM2.5 during their entire pregnancy, the likelihood of developing preeclampsia increases by about 50%," Beverly said in an institute news release.
The researchers also found that women who live within a quarter mile of a major roadway or in areas with high levels of traffic may be at an increased risk for preeclampsia.
Vehicle pollution is known to be major risk factor for heart disease, including hypertension.
Hypertensive disorders of pregnancy occur in more than 10% of pregnancies worldwide and are a leading cause of pregnancy-related illness and death.
Four distinct types
Women with hypertension during pregnancy are at increased risk for preterm delivery, and their infants are at greater risk for low birth weight and a number of long-term health problems associated with premature birth, according to the American College of Obstetrics and Gynecology.
"Hypertensive disorders of pregnancy refer to a range of clinical conditions, all of which include high blood pressure during pregnancy," Beverly said. "The disorders are classified into four distinct types, based on differences in the timing and onset of the symptoms."
The disorders include gestational hypertension (high blood pressure in the second half of pregnancy); preeclampsia (high blood pressure with protein in urine or impaired liver or kidney function in the second half of pregnancy); chronic hypertension (high blood pressure before and throughout pregnancy), and chronic hypertension with preeclampsia.
If preeclampsia worsens and causes seizures, it becomes eclampsia, a serious condition for woman and foetus that's potentially fatal.
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