Fertility treatment failure linked to air pollution

Women exposed to high levels of air pollution may have less success getting pregnant with fertility treatments or staying pregnant

Women

exposed to high levels of air pollution may have less success getting pregnant with fertility treatments or staying pregnant, compared to women breathing cleaner air, a South Korean study suggests.

Researchers analyzed pregnancy rates over nine years and more than 6,600 IVF cycles at a Seoul fertility clinic and found reduced conception rates and increased pregnancy losses among women exposed to the highest levels of five types of air pollution.

“Although the specific mechanism is unclear, high ambient air pollution has been suggested to affect processes of conception assisted by in vitro fertilisation ( IVF), which means the impact of air pollution can be profound in couples who are suffering from infertility,” said lead author Dr. Seung- Ah Choe of the School of Medicine at CHA University and the CHA fertility clinic in Seoul.

Past research has linked high concentrations of air pollutants produced by combustion of fossil fuels or wood to heart disease, stroke and inflammation, as well as infertility, the researchers note in Human Reproduction. To see if pollution affects the success of fertility treatment, the researchers examined records for 4,581 women who underwent one or more IVF cycles from 2006 through 2014. They also used districtlevel pollution- monitoring data from 40 sites around the city to estimate each woman's average hourly exposure during her fertility treatments to nitrogen dioxide, carbon monoxide, sulfur dioxide, ozone and tiny pollution particles known as PM 10.

These are major constituents of emissions from traffic vehicles, construction or industrial sites, Choe said in an email.

The researchers examined the effects of each pollutant at each of four stages in the IVF process.

Starting with ovarian stimulation to retrieve eggs, followed by embryo transfer to the uterus, then a hormonal test to detect early pregnancy and a later test to confirm ongoing pregnancy.

The women's average age was 35 and half of them had two or more embryos transferred over the entire course of their IVF treatments.

Overall, about 51 per cent achieved any pregnancy.