Penn State logoThat pollution seems to cause a number of ailments may not surprise many. However exposure to augmented levels of air pollutants, nitrogen dioxide in particular has now been associated to lower chances of a successful pregnancy among those going through in vitro fertilization (IVF). At least that’s what a team of fertility experts reveal.

As part of the study, the team analyzed the results of the first pregnancy attempt of approximately 7,403 women undergoing IVF. These women were submitted to the infertility treatment at Penn State Milton S. Hershey Medical Center, Hershey, Pa.; Shady Grove Fertility, Rockville, Md.; and Columbia University College of Physicians and Surgeons, New York, N.Y. The observations were conducted over a seven-year period from 2000 to 2007.

“Numerous studies have consistently shown a relationship between air pollution and human health, ranging from mortality, cardiovascular disease and other chronic conditions,” mentioned Duanping Liao, Ph.D., professor of epidemiology and vice chair department of public health sciences, Penn State College of Medicine. “In the process of searching for the mechanisms responsible for the above associations, we, and others, have reported significant links between air pollution and inflammation and increased blood clotting. These intermediate factors are also associated with reproductive health.”

The scientists claim to have picked on the IVF population as the process is known to be a well-controlled and timed one. It should thus help them in scrutinizing the link between air pollution and human reproductive effects. Nitrogen dioxide and fine particles are produced during burning of fossil fuels and diesel engine combustion. Along with ozone that involves smog formation, these pollutants were investigated.

The effects of backsliding air quality on IVF success may be variable and dependent on pollutants. Nevertheless increased exposures to nitrogen dioxide and fine particles appear to be regularly associated with decreased success rates of pregnancy. The effects of pollution particles were analyzed both individually in a single pollutant model and with other particles namely in a multi-pollutant model.

Exposure to ozone for the single pollutant model seemed to have a positive link to a successful birth. Though, this was when the exposure was prior to embryo culture or transfer of the embryo. According to the scientists, higher ozone levels may be an indication of lower nitrogen dioxide levels, which would display better pregnancy results. Additionally, for the multi-pollutant model, the ‘positive’ effects of ozone were dwindled with the addition of nitrogen dioxide.

Contrarily, post adjustment for ozone, elevated nitrogen dioxide exposures appeared to have been consistently associated with the lower success rate. This was irrespective of the indictor used. Positive pregnancy test reveals to have clinically confirmed intrauterine pregnancy or live birth. These findings could be useful in studying the adverse effects of air pollution on human reproduction in general.

The results of this study are published in ‘Human Reproduction.’