How increased risk of infertility due to pollution differs in men, women: Study

New Delhi: Men could be at a higher risk of infertility if exposed to PM2.5 pollution for a long term, while among women, the risk of infertility could increase from long-term exposure to road traffic noise, according to a study published in the British Medical Journal.

While researchers said that more studies are needed to confirm these findings, the study's results could help in forming strategies for regulating noise and air pollution, of which one of the health benefits could be higher fertility.

A major global health problem, infertility is estimated to affect one in every six people of reproductive age in their lifetime, according to the World Health Organization.

In men, infertility is most commonly caused by a low count or quality of sperms or by problems in the ejection of semen, while in women, infertility could be caused by abnormalities affecting varied parts related to reproduction, such as ovaries, uterus, or the endocrine system, according to the UN's public health agency.

Air pollution has been previously studied to affect sperm quality and reproductive success following fertility treatment.

However, the team, including researchers from the Danish Cancer Institute, Denmark, said that no studies have looked at how pollution affects infertility in men and women.

For the study, the researchers analysed data from national registers for over 5.2 lakh men and 3.7 lakh women aged 30-45 years, having fewer than two children and residing in Denmark during the study period from 2000 to 2017. Each participant was followed for an average duration of four years.

The specific study group was chosen to include a high number of people actively trying to become pregnant, and thus possibly at risk of being diagnosed with infertility, the authors said.

Average PM2.5 and road traffic noise levels at each participant's address for every year from 1995 to 2017 were calculated and data on infertility diagnosis were taken from the national patient register. In the study group, 16,172 men and 22,672 women were diagnosed with infertility.

The researchers found that among men aged 30-45 years, every three micrograms per cubic metre increase in average PM2.5 levels over five years was linked with a 24 per cent higher risk of infertility.

Among women older than 35 years, every 10.2-decibel increase in average road traffic noise levels of five years was associated with a 14 per cent higher risk of infertility, the authors found. Women younger than 35 years were not affected.

Road traffic noise was also found to be associated with a small increased risk of infertility in men in the 37-45 age group, but not among those aged 30-37 years.

Being an observational study, the authors could not establish the causes for these links between air and noise pollution and infertility.

They also acknowledged that information on the participants' lifestyle, including exposure to pollution at work and during leisure activities was lacking.