Low Sperm Count?: Lifestyle Factors That Affect Risk taken from Medscape

CLINICAL CONTEXT
Many men are affected by subfertility, and a study by Guzick and colleagues, which appeared in the November 8, 2001, issue of the New England Journal of Medicine, compared sperm morphology, motility, and concentration among fertile and infertile men. None of these variables alone was a powerful discriminator for fertility. Infertility was associated with a rate of sperm motility of less than 32%, and rates of normal sperm morphology in excess of 12% were associated with normal fertility.

Improving modifiable risk factors for sperm abnormalities can reduce the rate of subfertility among men, but which of these factors is significant? The current study by Povey and colleagues addresses this issue.

STUDY SYNOPSIS AND PERSPECTIVE
Common lifestyle factors associated with low-motile sperm concentration (MSC) include a history of testicular surgery, black ethnicity, and being involved in manual labor, but no association was found with smoking, drugs, or alcohol use, according to new research.

Andrew C. Povey, PhD, from the Centre for Occupational and Environmental Health at the University of Manchester, United Kingdom, and colleagues reported their findings in an article published online June 13 in Human Reproduction.

According to the researchers, the "understanding of how the lifestyle choices of adult men themselves might impact on their fertility remains uncertain and often contradictory."

The current study examined lifestyle data of men recruited to the large multicentre Chemical and Pregnancy Study to identify factors that may contribute to low sperm count.

Participants included men who were part of a couple who had been attempting conception without success after at least 12 months of unprotected intercourse.

The authors collected data on 780 men with low MSC as well as data from 1469 referents (ie, men attending a fertility clinic who did not have low MSC). Participants were requested to abstain from ejaculation for a period of 3 to 5 days (depending on the clinic) before the clinic visit at which sperm count was measured. Low sperm count was defined as fewer than 12 × 106/mL motile sperm (moving forward at 5 μm/second or greater).

Risk factors for low MSC included a history of testicular surgery (odds ratio [OR], 2.39; 95% confidence interval [CI], 1.75 - 3.28), being in manual work (OR, 1.28; 95% CI, 1.07 - 1.53), being unemployed (OR, 1.78; 95% CI, 1.22 - 2.59), and having black ethnicity (OR, 1.99; 95% CI, 1.10 - 3.63).

According to the researchers, the increased risk in men of black ethnicity is of interest, but "the numbers are small and hence no strong conclusion can be reached."

It also remains unclear, after controlling for exposure to glycol ethers and other toxicants, why manual labor may contribute to low MSC, the authors note.

Conversely, consistent with some previous findings, men who wore boxer shorts (OR, 0.76; 95% CI, 0.64 - 0.92) or who had previously conceived a child (OR, 0.71; 95% CI, 0.60 - 0.85) were less likely to have a low MSC.

"No significant association was found with smoking and alcohol consumption, the use of recreational drugs, a high [body mass index,] or having a history of mumps or fever," the researchers report.

According to the researchers, the power of the study was sufficient to draw conclusions about common lifestyle choices, but the findings are less clear regarding exposures that are perhaps rare and poorly reported.

The "finding that use of street drugs was unrelated to low MSC cannot be assumed to apply to all such drugs and all patterns of use," Dr. Povey and colleagues write. "The case definition did not consider sperm morphology or sperm DNA integrity," they add.

The researchers note that their "study shows that common lifestyle choices, other than wearing tight underwear, make little contribution to MSC and that delaying assisted conception to make poorly evidenced changes to lifestyle is unlikely to enhance conception and may indeed be prejudicial in couples with little time to lose."

The study was funded by the UK Health and Safety Executive; the UK Department of Environment, Transport and the Regions; the UK Department of Health; and the European Chemical Industry Council. The authors have disclosed no relevant financial relationships.

Hum Reprod. Published online June 13, 2012. Abstract

STUDY HIGHLIGHTS
Men 18 years or older were recruited from 14 fertility clinics in the United Kingdom for the study. All participants had experienced infertility after at least 12 months of trying to conceive.
All participants performed a semen analysis. The original cutoff value for subfertility was less than 12 × 106/mL progressively motile sperm, and the cutoff value was changed during the study period to progressive values based on the participants' duration of abstinence before semen analysis.
The main study outcome was the association between demographic, health habit, and physical risk factors and the finding of subfertility.
2249 men provided background information as well as a semen analysis, and 939 men were found to be subfertile.
Nonmodifiable risk factors significantly associated with subfertility were black race vs white race (OR, 1.99; 95% CI, 1.10 - 3.63) and a history of testicular surgery (OR, 2.39; 95% CI, 1.75 - 3.28).
Modifiable risk factors associated with subfertility included unemployment (OR, 1.78; 95% CI, 1.22 - 2.59) and manual work (OR, 1.28; 95% CI, 1.07 - 1.53).
Wearing boxer shorts (OR, 0.76; 95% CI, 0.64 - 0.92) and a history of previous conception (OR, 0.71; 95% CI, 0.60 - 0.85) were associated with a significantly reduced rate of subfertility.
Smoking, alcohol consumption, and the use of recreational drugs were not significantly associated with the rate of subfertility.
Similarly, body mass index failed to affect the rate of subfertility on adjusted analyses.
A history of mumps or fever during the 3 months before semen analysis also failed to affect the rate of subfertility.


CLINICAL IMPLICATIONS
In a previous study by Guzick and colleagues that compared sperm morphology, motility, and concentration among fertile and infertile men, none of these variables alone was a powerful discriminator for fertility. Infertility was associated with a rate of sperm motility of less than 32%, and rates of normal sperm morphology in excess of 12% were associated with normal fertility.
Risk factors for subfertility among men in the current study by Povey and colleagues included manual work, wearing tight underwear, a history of testicular surgery, and black race. Smoking, alcohol consumption, and the use of recreational drugs were not significantly associated with the rate of subfertility.