Exposure to Smog in Early Pregnancy Linked to Complications02/07/13
WEDNESDAY, Feb. 6 (HealthDay News) -- Women exposed to elevated
levels of ozone air pollution in the first three months of
pregnancy may be at increased risk for complications such as
preeclampsia and premature birth, a new study suggests.
Mothers with asthma may be most vulnerable, according to the
report published in the Feb. 6 online edition of the journal
Preeclampsia occurs when a woman develops high blood pressure
and protein in the urine after the 20th week of pregnancy. Left
untreated, it can cause serious complications. Premature birth is
delivery before 37 weeks of pregnancy, the study authors noted in
For the study, David Olsson, of the department of public health
and clinical medicine at Umea University in Sweden, and colleagues
looked at data from nearly 121,000 single-baby pregnancies in
Stockholm between 1998 and 2006, as well as air pollution records
for the city during that time. Preeclampsia occurred in 2.7 percent
of the pregnancies and 4.4 percent of them resulted in a premature
birth, the investigators found.
There was no association between levels of vehicle exhaust
exposure and pregnancy complications, nor between any air
pollutants and low birth weight among the babies, the study authors
noted in a journal news release.
However, the researchers did find evidence of a link between
exposure to ozone air pollution during the first three months of
pregnancy and the risk of preeclampsia and premature birth. The
risk for each rose by 4 percent for every 10 micrograms per cubic
meter rise in exposure to ozone during the first trimester.
About one in 20 cases of preeclampsia was linked to ozone
exposure during early pregnancy, according to the report.
The study also found that mothers with asthma were 10 percent
more likely to develop preeclampsia and 25 percent more likely to
have a premature birth than those without asthma.
Although the study found an association between first-trimester
exposure to high ozone levels and preeclampsia and premature birth,
it did not prove a cause-and-effect relationship.
The U.S. National Institute of Child Health and Human
Development has more about
preeclampsia and eclampsia.
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