Washington D.C. [USA], June 27 : High levels of air pollution adversely affect a potential marker of female fertility called ovarian reserve, a term used to indicate the number of resting follicles in the ovary, finds a study.
The study, presented at 'ESHRE 35th annual meeting, used hormone measurements taken from more than 1,300 Italian women to reach the conclusion.
Behind the study lay emerging evidence that many environmental chemicals, as well as natural and artificial components of the everyday diet, have the potential to disturb the physiological role of hormones, interfering with their biosynthesis, signalling or metabolism.
The hormone, in this case, anti-Mullerian hormone or AMH, is secreted by cells in the ovary and is now widely recognised as a reliable circulating marker of ovarian reserve.
"The influence of age and smoking on AMH serum levels is now largely accepted but a clear effect of environmental factors has not been demonstrated so far," says Antonio La Marca, the study's first investigator.
The study is, in effect, an analysis of all AMH measurements taken from women living in Modena area between 2007 and 2017, and assembled in a large database.
The analysis was completed with environmental data and a 'geo-localisation' estimate based on each patient's residence.
The assessment of environmental exposure considered the daily particulate matter (PM) and values of nitrogen dioxide (NO2), a polluting gas which gets into the air from burning fuel.
Results from the 1463 AMH measurements collected from 1,318 women firstly showed, as expected, that serum AMH levels after the age of 25 were inversely and significantly related to the women's age.
It was, however, also found that AMH levels were inversely and significantly related to environmental pollutants defined as PM10, PM2.5, and NO2. This association was age-independent.
While noting that this study again confirms that age is the most important determinant of AMH concentration in women, La Marca emphasises that other factors such as smoking, body weight, and long-term hormonal contraception are already recognised as having an impact on AMH.
Similarly, he adds, environmental pollutants may also have a significant effect in determining circulating levels of AMH.
"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 2 or 3," adds Marca.