Long-term exposure to traffic noise and air pollution linked to increased infertility risk

By Dr. Priyom Bose, Ph.D.Reviewed by Benedette Cuffari, M.Sc.Sep 9 2024

Traffic Noise and Air Pollution Could Be Hurting Your Fertility: New Study Uncovers Surprising Risks for Men and Women.

Study: Long term exposure to road traffic noise and air pollution and risk of infertility in men and women: nationwide Danish cohort study. Image Credit: Dennis MacDonald / Shutterstock.com

A recent BMJ study explores the associations between long-term exposure to road traffic noise, air pollution, and infertility in men and women.

Risk factors for infertility

Infertility is a major global health problem that is defined as a lack of conception after unprotected and regular sexual intercourse for one year. Infertility has also been associated with long-term adverse health effects, including an increased risk of stress, anxiety, and depression.

Several risk factors for infertility are similar between both men and women, of which include advanced age, tobacco and alcohol use, chronic conditions and diseases, and obesity. Exposure to air pollution, pesticides, and ionizing radiation may also increase the risk of infertility.

Previous research has shown that particulate air pollution is negatively correlated with sperm count, motility, and morphology. Exposure to air pollution can also reduce the success rate of fertility treatment in women.

Like air pollution, road traffic noise has been associated with various chronic diseases. Noise activates the autonomic nervous system and hypothalamic-pituitary-adrenal axis, thereby inducing a stress response.

Noise pollution can cause sleep disruptions which, coupled with stress, can negatively impact reproductive function. Nevertheless, there remains a lack of research examining the impact of noise on fertility.

About the study

The current nationwide prospective cohort study was conducted in Denmark and comprised 526,056 men and 377,850 women between 30 and 45 years of age. All men and women included in the study were married or cohabiting, had fewer than two children, and were residents of Denmark between 2000 and 2017.

The primary objective of the current study was to assess whether a higher risk of infertility was associated with long-term exposure to pollution from particulate matter with a diameter of less than 2.5 micrometers (µm) (PM_2.5) and road traffic noise.

The Danish National Patient Register was used to obtain data on individual-level noise, air pollution, and socioeconomic variables. Data from the Building and Housing Register were analyzed to obtain participant residential addresses for estimating road traffic noise and air pollution.

Study findings

In the study cohort, 16,172 men and 22,671 women were diagnosed with infertility during an average follow-up period of 4.3 and 4.2 years, respectively. Distributions of exposure levels to noise and air pollution were similar across men and women.

Exposure to PM_2.5 was associated with a higher risk of infertility in men across all age groups. In men between 30 and 36.9 years of age, no association was observed between noise and infertility; however, the consideration of PM_2.5 into this relationship led to a hazard ratio of less than one. In men between 37 and 45 years of age, infertility risk was slightly higher with noise exposure, irrespective of PM_2.5 adjustment.

Women between 35 and 45 years of age were at a greater risk of infertility when they were exposed to noise, whereas no association was observed in women between 30 and 34.9 years of age. Across both age groups, infertility risk was not associated with exposure to PM_2.5. Adjusting for other covariates did not significantly alter these relationships.

Among women between 35 and 45 years of age, noise was associated with a higher risk of anovulation, tubal factor, and unknown cause. Across both age groups, unknown infertility correlated with PM_2.5 exposure.

Among men of both age groups, higher PM_2.5 exposure was associated with an increased risk of oligospermia, azoospermia, and unknown infertility. In men between 37 and 45 years of age, noise was associated with an increased risk of unknown infertility. Comparatively, noise was weakly associated with a reduced risk of azoospermia and unknown infertility in men between 30 and 36.8 years of age.

The increased risk of PM_2.5-related infertility in men and noise-related infertility in women were consistent, regardless of whether the individual resided in urban, suburban, and rural areas, as well as those of high, medium, and low socioeconomic status. For noise, stronger associations with infertility were observed among those without a silent facade at home.

Conclusions

High exposure to air pollution was associated with a greater risk of infertility in men, whereas a higher infertility risk was observed among women 35 years of age and older exposed to road traffic noise. The association between traffic noise and infertility in older men was weak.

Future studies are needed to validate the current study findings. Nevertheless, these observations suggest the need for air pollution and noise mitigation policies to improve birth rates in western countries.