Global decline in sperm counts is accelerating, research finds

A global decline in sperm counts first identified in 2017 is accelerating, according to research that shows the phenomenon seen in other parts of the world is also affecting men in South America, Asia and Africa.

The analysis carried out by Professor Hagai Levine of Hebrew University of Jerusalem and Professor Shanna Swan at the Icahn School of Medicine in New York, found that the average sperm count globally more than halved between 1973 and 2018.

Since 1972 it had fallen by about 1 per cent each year, the researchers said. However since 2000, the annual decrease had been, on average, more than 2.6 per cent.

Levine said the findings served “as a canary in a coal mine”. “We have a serious problem on our hands that, if not mitigated, could threaten mankind’s survival,” he said.

The paper, published in the journal Human Reproduction Update on Tuesday, was based on data from 53 countries and included statistics collected since the earlier study. It focused on sperm count trends among men in South America, Asia and Africa, regions not examined in the earlier report.

Men in those regions shared the significant decline in total sperm counts and sperm concentration seen previously in North America, Europe and Australia, the researchers reported.

Levine said: “Overall, we’re seeing a significant worldwide decline in sperm counts of over 50 per cent in the past 46 years, a decline that has accelerated in recent years.”

While the study did not examine the causes of these declines, Levine pointed to recent research indicating that disturbances in the development of the reproductive tract in the womb were linked to “lifetime impairment of fertility and other markers of reproductive dysfunction”. He called for global action “to promote healthier environments for all species and reduce exposures and behaviours that threaten our reproductive health”.

Swan said the accelerated decrease in global sperm counts meant “more people will need to use assisted reproduction to conceive”. The implications went beyond decreased fertility since lower sperm counts were “linked to more disease later in life — cardiovascular disease, diabetes and reproductive cancers — and a shorter life expectancy”. 

The decline was too rapid to be due to genetic causes alone, she argued, pointing out that some risk factors for lower sperm counts had to do with lifestyle factors such as diet, smoking, obesity, stress and binge drinking. But she highlighted the role of environmental chemicals, particularly those with the ability to affect the steroid hormones, which are critical for reproduction.

Most important were the “endocrine-disrupting” chemicals that could alter levels of testosterone and oestrogens such as the phthalates — found in hundreds of cleaning and personal care products — and the bisphenols (BPA) which often form part of containers used to store food and drinks, such as water bottles. These were “critically involved in reproductive function”, Swan added.

She urged men to avoid “smoking, a sedentary lifestyle, excessive weight gain, drug and alcohol abuse and potentially toxic chemicals”.