Exposure to environmental air pollutants may decrease a woman's ovarian reserve, suggests a new study.
'Living in an area associated with high levels of air pollutants in our study increased the risk of severely reduced ovarian reserve by a factor of two or three,' said Professor Antonio La Marca from the University of Modena and Reggio Emilia in Modena, Italy.
He presented the findings of the retrospective study to the European Society for Human Reproduction and Embryology's annual meeting in Vienna, Austria.
The researchers used a 'big data' approach to link hospital hormone measurements for more than 1300 Italian women in Modena with real-time environmental data on levels of nitrogen dioxide and particulate matter from the regional authorities, along with geo-location data using Google Maps and the women's addresses.
The researchers used levels of anti-Müllerian hormone (AMH) as a marker of ovarian reserve, in women living in the urban area between 2007-2017.
As expected, AMH levels decreased with age, they were also inversely related to environmental pollutants released by the burning of fossil fuels, and his association was independent of age. Hormone levels indicating a severe reduction were more frequent at the highest levels of exposure.
'The higher the exposure to these molecules, the lower the AMH,' said Professor La Marca.
He said that 'severe ovarian reserve reduction' - was seen in subjects who were exposed to high levels of the pollutant nitrogen dioxide, as well as particulates PM10 and PM2.5, which were nonetheless well below the upper limits recommended by the EU and local authorities.
'This study reveals the impact of air pollution on a woman's ovarian reserve, but it is yet unclear if this impact is permanent and if it detrimentally influences conception per se,' said Ying Cheong, Professor of Reproductive Medicine at the University of Southampton. 'It is not yet known if this translates into a higher incidence of infertility in geographical locations where the pollution rate is higher.'
Richard Anderson, Professor of Clinical Reproductive Science at the University of Edinburgh called the study 'interesting and potentially important'. He added: 'However this sort of study cannot clearly show cause and effect, and it might be another aspect of the women's lifestyle or environment that is the key factor.'