1. The more medications a man took was associated with higher risk of low sperm count.
2. Occupational exertion was also associated with lower semen quality, though other workplace exposures were not.
Evidence Rating Level: 2 (Good)
Study Rundown: Infertility is a problem affecting up to 15 percent of couples. Historically, the majority of fertility evaluation has centered on female causes of infertility. For example, semen analysis was not a routine part of a couple’s infertility evaluation until the mid to late 1980’s. However, up to 40% of infertility is attributable to male causes. Male factor infertility can be due to a combination of factors including low sperm production, abnormal sperm function, or blockages that block sperm delivery. Given the sensitivity of spermatogenesis to chemotherapy and other toxicities, researchers postulated that environmental exposures, such as those encountered in the workplace, impact semen quality. Previous investigations on this topic have been poor quality and focused on chemical exposures. Few high quality studies assessing work-related factors such as exertion, heat, vibration and prolonged sitting exist. The present study is the first prospective study to assess the relationship between physical occupational hazards and male infertility.
Having high blood pressure, taking many medications and having an occupation requiring significant exertion were associated with lower semen quality. Strengths include the prospective design and population-based sampling. Results are limited by reporting bias due to self-reported workplace exposures and medical history. Future interventional studies assessing the impact of altering these modifiable lifestyle habits on semen parameters would lend credence to the associations identified herein.
In-Depth [prospective cohort]: As part of the Longitudinal Investigation of Fertility and the Environment (LIFE) Study, 501 couples trying to conceive were followed for one year. Men completed baseline interviews including information on occupation, lifestyle and health and provided a semen sample to assess the relationship between work exposures and health on semen quality. Complete data was available for 453 men (90%).
Oligospermia was more common among men taking two or more medications compared to men taking no medications (15% vs. 7%, p < 0.05). Men who reported heavy exertion at work were more likely to display oligospermia (low sperm count) than men who did not. High blood pressure was associated with an insignificantly lower morphology score compared with normotensive men. Hyperlipidemia, diabetes as well as shift work, night work, vibration at work, noise, heat and prolonged sitting were not associated with semen quality.
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