Smoking and Drinking May Not Harm Male Fertility

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Doctors often recommend lifestyle changes for men facing infertility: avoid cigarettes, cut back on drinking, lose weight. That’s great advice for an overall healthy life, but a new study suggests it won’t necessarily help men conceive a child.

Researchers at the University of Manchester and the University of Sheffield in the U.K. say that doctors might want to reconsider their advice to infertile men given the new findings: if infertile couples are delaying fertility treatments in order to try ineffective lifestyle changes first, it may waste valuable time and fail to help them conceive.

For their study, the researchers recruited 2,249 men from 14 fertility clinics around the U.K. The men filled out detailed questionnaires about their lifestyle habits, including their smoking and drinking behaviors, along with other factors like their weight, the type of work they did and whether they wore tight-fitting underwear. The data were then compared between 939 men who produced low numbers of swimming sperm and the control group of 1,310 men who produced higher numbers.

Although swimming sperm count is not the only measure of a man’s sperm quality, the researchers note that it broadly correlates with how fertile he is likely to be and also helps determine what type of fertility treatment he may receive.

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Compared with men who produced high numbers of swimming sperm, those whose counts were low were 2.5 times more likely to have had testicular surgery, twice as likely to be of black ethnicity, and 1.3 times more likely to be in manual work, to not wear boxer shorts, and to have not conceived previously.

Based on the data, researchers further found that lifestyle factors like use of recreational drugs, smoking, drinking and body weight had little effect. For instance, the proportion of men with low swimming sperm counts was similar whether they smoked over 20 cigarettes a day or if they had never smoked before. Alcohol use was also unrelated to fertility among men.

“The message of ‘No smoking, drinking in moderation, no street drugs and not be too overweight’ is clearly sound and should be offered to men as good health advice,” says study author Dr. Andrew Povey of University of Manchester’s School of Community Based Medicine. “However, the evidence from this study is that even if the man changes his lifestyle in such a fashion, such changes are unlikely to improve his chances of conceiving a child.”

The findings came as a surprise to the researchers. “I expected to find a link with smoking, as studies have often reported that smoking is bad for semen quality,” says Povey. “When I looked again at the evidence for such statements, I found that it wasn’t necessarily that strong and that if there was an effect of smoking, it was more likely to occur within the normal range of semen quality and not then directly affect whether a man was likely to be infertile or not.”

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The factors that were associated with poor sperm quality like not wearing boxer shorts and participating in manual labor are not fully understood. But previous research has shown that job-related exposures to chemicals or other substances can affect sperm quality. As for the underwear finding, that’s an easier change. “Our results suggest that the type of underwear a man wears can help to determine the level of swimming sperm. So, as it is a relatively easy thing to change, with little risk, wearing boxer shorts might help,” says Povey.

Although researchers didn’t find a connection between lifestyle choices and swimming sperm counts, they acknowledge that unhealthy habits could still be linked to other aspects of sperm quality, such as the size and shape of sperm as well as the quality of the DNA they carry — factor that have also been linked to male infertility.

The study was published in the medical journal Human Reproduction.

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