A new study released by the National Institutes of Health reveals that effects from air pollution could increase the risk of early pregnancy loss.
"We've studied air pollution and reproductive health for several years, it's an area of research for myself and my team," said Pauline Mendola, Ph.D., the lead author of the study and a researcher at NIH's National Institute of Child Health and Human Development.
Mendola explained that after she and her colleagues published a paper earlier this year that revealed that exposure to ground-level ozone was associated with stillbirth, they were curious to see whether the same pollutants could be correlated with miscarriage as well. The study concluded that couples exposed to air pollution were more likely to experience a loss in early-stage pregnancies.
The researchers looked at 501 volunteer couples between 2005 and 2009 in 16 counties across Texas and Michigan who were either married or in a committed relationship, not diagnosed with infertility, and were using neither contraception nor any hormonal treatments that would enhance fertility. Female participants also needed to be between the ages of 18 and 40 while male participants had to be age 18 or older.
Mendola explained that because studies like hers are conducted on volunteers, the results have limitations because drawing a sample from volunteers is not the same as a random sample drawn from the population at large.
"The people who volunteer are not representative of the general population," she said. "These volunteers are more likely to be white, to be socially advantaged and to have more education."
After participants were exposed to a variety of pollutants – including carbon monoxide, nitrogen oxides, nitrogen dioxide, sulfur dioxide and ozone – results showed that 97 of 343 pregnant couples experienced early pregnancy loss.
"We found in our study that there were almost a hundred losses and about nine of those might have been prevented if the exposure to those air pollutants were lower," Mendola said.
While the study found there was a correlation between air pollution exposure and pregnancy loss, Mendola cautioned that she and her colleagues did not know what caused the couples to lose the pregnancies.
"The general thought would be that it is something related to stress or inflammation that could be systemic as a result of the exposure to these compounds," she said. "But that's something we really need more work on to try and understand what the biological mechanisms are."
Speaking to the significance of her study, Mendola hoped her results might lead to additional research that would establish the exact causes of pregnancy loss.
"If we can find that ambient air is a contributor, even if it's very small, it's a ubiquitous exposure," she said. "So if we can find things that can be mitigated then that's a benefit to the population."