A study has found that air pollution is linked to a higher risk of infertility in men, while noise pollution is linked to a higher risk of infertility in women.
The studypeer-reviewed study published in the BMJ investigated whether long-term exposure to traffic noise and fine particulate matter (PM2.5), a type of air pollution, was associated with an increased risk of infertility in men and women.
The data come from a database of 526,056 men and 377,850 women aged 30 to 45 who had fewer than two children, were cohabiting or married, and who lived in Denmark between 2000 and 2017. This subset of the database was selected to include a large proportion of people who were actively trying to conceive.
The study excluded sterilized men and women who had undergone surgery to prevent pregnancy.
Between 1995 and 2017, the average amount of PM2.5 pollution was recorded at each participant’s addresses and infertility diagnoses were recorded from the national patient register.
During the 18-year period, infertility was diagnosed in 16,172 men and 22,672 women. After adjusting for factors such as income, education and occupation, exposure to PM2.5 levels 2.9 micrograms per cubic meter higher than the five-year average was associated with a 24% higher risk of infertility in men aged 30 to 45.
While PM2.5 was not associated with infertility in women, exposure to traffic noise levels 10.2 decibels higher than average over five years was associated with a 14% higher risk of infertility in women over 35, while in women aged 30 to 35, noise was not associated with infertility.
Traffic noise was associated with a slightly increased risk of male infertility in people aged 37 to 45 years, but not in people aged 30 to 37 years.
One in seven couples in the UK trying to conceive experience infertility.
The researchers said that several previous studies had found negative associations between particulate matter air pollution and sperm quality, but that these studies were inconsistent.
They concluded: “Based on a nationwide cohort designed to include a large proportion of people actively trying to conceive, we found that PM2.5 was associated with a higher risk of an infertility diagnosis in men and that traffic noise was associated with a higher risk of an infertility diagnosis in women aged over 35 years, and possibly in men aged over 37 years.
“As many Western countries are experiencing declining fertility rates and increasing maternal age at first childbirth, knowledge about environmental pollutants that affect fertility is crucial. If our results are confirmed in future studies, this suggests that political implementation of air pollution and noise restrictions could be important instruments to improve fertility rates in the Western world.”