News | Long-Term Review Finds Heat, Stress, and Other Physical Factors May Affect Male Infertility
A study published in The Archives of Italian Urology and Andrology examined how work-related physical risk factors affect male infertility. It offers insight into possible causes and how occupational exposures may affect male fertility.
Background and purpose
The World Health Organization (WHO) defines infertility as failure to achieve pregnancy after one year or more of regular unprotected intercourse. About 15% of couples worldwide experience infertility, and male factors account for one-third of cases. Rates vary by region and are highest in Central and Eastern Europe and Africa.
The review examined two decades of research on how physical factors affect male fertility. The team searched for studies involving radiation, heat, physical labor, stress, and prolonged sitting and assessed their associations.
Methods and data
Researchers identified 872 publications, selected 80 for full-text review, and included 36 after removing duplicates and ineligible studies.
Among bakers in Saudi Arabia, men exposed to a wet-bulb temperature of 37°C had an infertility rate of 22.7%, compared with 3% among healthy volunteers. Steelworkers exposed to a wet-bulb temperature of 36°C had significantly poorer semen parameters, including morphology, count, motility, and volume, than unexposed workers. Some studies found that semen-quality impairment reversed after heat exposure ended.
Moderate physical activity, reduced stress, and good health may increase the chance of pregnancy, while excessive physical labor may cause stress and affect fertility. One study reported increases in seminal cytokines and reactive oxygen species after both aerobic and static anaerobic exercise.
Semen quality was also affected in mountaineers above 2000 meters, where hypoxia is a risk. Professional athletes, including soccer and rugby players, had increased seminal neutrophils and superoxide dismutase (SOD) after matches and at season's end.
Effects of radiation on male fertility
Experiments showed damage to spermatogonia and sperm after exposure to 2-3 Gray (Gy) and 4-6 Gy, with 3-5 Gy potentially causing permanent infertility. Exposure below 1 Gy usually allowed full recovery within 18 months, while recovery after 4-6 Gy could take 5 years or longer.
A study of mobile-phone use found a lower proportion of rapidly motile sperm among men using a phone for more than one hour daily. Norwegian Navy personnel exposed to radiofrequency electromagnetic fields also faced higher fertility risks.
Effects of prolonged sitting and stress
Sedentary work increased scrotal temperature by an average of 0.7°C and by up to 2.2°C in drivers. Each 1°C increase in scrotal temperature was associated with a 40% decline in sperm concentration. Stress was negatively associated with semen parameters, sperm count, and concentration. Men experiencing at least two major life events had significantly lower sperm concentration and count. Among university students, sperm concentration fell before examinations while seminal superoxide dismutase and nitric oxide levels rose.
Conclusions and recommendations
Although physical factors are associated with male infertility, current evidence is insufficient to define their effects conclusively. More research is needed to confirm these relationships and protect vulnerable workers.
News | Long-Term Review Finds Heat, Stress, and Other Physical Factors May Affect Male Infertility
News | Long-Term Review Finds Heat, Stress, and Other Physical Factors May Affect Male Infertility
A study published in The Archives of Italian Urology and Andrology examined how work-related physical risk factors affect male infertility. It offers insight into possible causes and how occupational exposures may affect male fertility.
Background and purpose
The World Health Organization (WHO) defines infertility as failure to achieve pregnancy after one year or more of regular unprotected intercourse. About 15% of couples worldwide experience infertility, and male factors account for one-third of cases. Rates vary by region and are highest in Central and Eastern Europe and Africa.
The review examined two decades of research on how physical factors affect male fertility. The team searched for studies involving radiation, heat, physical labor, stress, and prolonged sitting and assessed their associations.
Methods and data
Researchers identified 872 publications, selected 80 for full-text review, and included 36 after removing duplicates and ineligible studies.
Among bakers in Saudi Arabia, men exposed to a wet-bulb temperature of 37°C had an infertility rate of 22.7%, compared with 3% among healthy volunteers. Steelworkers exposed to a wet-bulb temperature of 36°C had significantly poorer semen parameters, including morphology, count, motility, and volume, than unexposed workers. Some studies found that semen-quality impairment reversed after heat exposure ended.
Moderate physical activity, reduced stress, and good health may increase the chance of pregnancy, while excessive physical labor may cause stress and affect fertility. One study reported increases in seminal cytokines and reactive oxygen species after both aerobic and static anaerobic exercise.
Semen quality was also affected in mountaineers above 2000 meters, where hypoxia is a risk. Professional athletes, including soccer and rugby players, had increased seminal neutrophils and superoxide dismutase (SOD) after matches and at season's end.
Effects of radiation on male fertility
Experiments showed damage to spermatogonia and sperm after exposure to 2-3 Gray (Gy) and 4-6 Gy, with 3-5 Gy potentially causing permanent infertility. Exposure below 1 Gy usually allowed full recovery within 18 months, while recovery after 4-6 Gy could take 5 years or longer.
A study of mobile-phone use found a lower proportion of rapidly motile sperm among men using a phone for more than one hour daily. Norwegian Navy personnel exposed to radiofrequency electromagnetic fields also faced higher fertility risks.
Effects of prolonged sitting and stress
Sedentary work increased scrotal temperature by an average of 0.7°C and by up to 2.2°C in drivers. Each 1°C increase in scrotal temperature was associated with a 40% decline in sperm concentration. Stress was negatively associated with semen parameters, sperm count, and concentration. Men experiencing at least two major life events had significantly lower sperm concentration and count. Among university students, sperm concentration fell before examinations while seminal superoxide dismutase and nitric oxide levels rose.
Conclusions and recommendations
Although physical factors are associated with male infertility, current evidence is insufficient to define their effects conclusively. More research is needed to confirm these relationships and protect vulnerable workers.
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Compiled from online sources