Researchers suspect that the strong magnetic fields produced by some electric appliances and vehicles increase the risk of miscarriage. ?The studies really represent state-of-the-art research into the causes of pregnancy loss,? says epidemiologist David Savitz of the University of North Carolina.
A study led by De-Kun Li, a reproductive epidemiologist at the Kaiser Foundation Research Institute in Oakland, California, asked 1,063 women around San Francisco who were in the first 10 weeks of pregnancy to spend a day wearing a meter around their waists that measured magnetic field levels every 10 seconds.
They found that women exposed to peak levels of 1.6 microteslas or greater were nearly twice as likely to miscarry as women not exposed to such strong fields. Among the 622 women who said the measuring period had been a typical day, those who experienced high peak fields were three times as likely to have a miscarriage. ?That?s another confirmation that the effect is due to EMF,? says Li.
Li?s team didn’t look at what was producing the fields, but appliances such as shavers, hairdryers and vacuum cleaners can produce strong alternating magnetic fields, as can electric vehicles such as trolleys and subway trains. The key is how close you are to the source, since fields drop off quickly with distance.
The few previous studies of the effect of low-frequency EMFs on miscarriages, such as one involving 727 women done in 1991 have been inconclusive. But Li thinks this is because they looked at people?s average exposure to electromagnetic fields over time, not the peaks they were exposed to daily. ?People have never looked at peak EMFs before,? Li says. ?My study opens a new chapter for these EMF effects. Not just for miscarriages, but for other health effects.? When Raymond Neutra, who did the 1991 study, reanalyzed his data, he discovered the results were similar to Li?s. Women exposed to peak EMF levels greater than 1.4 microteslas were nearly twice as likely to miscarry.
Savitz says, ?Both studies found a reassuring lack of association for the most well-established measures of magnetic field exposure, that is average magnetic fields.? This means that pregnant women do not have do avoid electricity entirely, which would be impossible. He feels that women who have a healthy pregnancy are more likely to suffer from nausea, which may make them more likely to stay at home and do less, and thus also reduce their exposure to magnetic fields.
In the past, EMFs have been blamed for various other illnesses, especially leukemia in children. But no one can explain how relatively weak fields might cause the DNA mutations that lead to cancer. Li says that EMF spikes could cause miscarriages by subtly disrupting cell-to-cell communication.
Michael Bracken, an epidemiologist at Yale University, says, ?There?s a real risk in these things getting over-interpreted and scaring the dickens out of people.? For instance, age can be a factor in miscarriages: The risk of a miscarriage increases ten times as women age, from 5 percent for women under 30 years old to 50 percent for those in their mid-40s.
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