Exposure to high levels of pollution from diesel exhausts during pregnancy could increase the risk of miscarriage, according to research.
The study, conducted in Brazil, found that diesel disrupts the development of cells, which could trigger the event, even at low levels of exposure.
Researchers from the University of Sao Paulo announced the results after looking at the effects exhaust particles, including PM10s, had on mice embryos.
Dr Paulo Marcelo Perin said: "Our latest study found that air pollution significantly decreased the cell population (of embryos)."
And while the study was carried out in Brazil, it is believed that the effects would be the same across the world. In the UK, the government has estimated that air pollution causes between 12,000 and 24,000 premature deaths each year.
The study follows previous research which found that women undergoing IVF who were exposed to pollution levels higher than the WHO recommended safe level were at a greater risk of pregnancy loss.
Dr Perin said: "We saw a significant increase in the miscarriage rates. There was a 2.5 fold increase in pregnancy loss when exposed to high levels of pollution."