Men who smoke not only have poorer sperm quality than nonsmokers, but also have lower sex drives and less frequent sex, investigators reported at the joint annual meeting of the American Society for Reproductive Medicine and the Canadian Fertility and Andrology Society, held in Toronto.

Dr. Panayiotis Zavos, professor of reproductive physiology and andrology, University of Kentucky, Lexington, and colleagues at other centers recruited 290 couples undergoing evaluation for infertility at the Andrology Institute of America. On their initial visit, couples were asked to complete a questionnaire detailing their smoking habits, and their marital and sexual history, including how often they had sex and their level of sexual satisfaction.

"In all couples that participated in the study, the females were nonsmokers," the investigators note. In contrast, in 158 couples, the male partners smoked at least 30 cigarettes a day and had smoked for more than 7 years.

Results from the questionnaire revealed that where the male partner smoked, the couple had been trying to conceive for 3.1 years compared with 2.6 years for nonsmoking couples, an observation that researchers felt was "biologically significant."

Smokers also reported having sex only 5.7 times per month compared with nonsmokers who had sex 11.6 times per month. "This is a very dramatic effect," Zavos told Reuters Health.

Nonsmoking couples also reported significantly greater satisfaction with their sex life, giving it an 8.7 on a scale of 0 to 10, 10 being "extremely satisfactory." In contrast, smoking couples gave their sex life a 5.2 rating on the same scale, the researchers note.

Results from semen analyses also revealed the quality of spermatozoa from nonsmokers was superior to that of smokers both in terms of sperm viability and longevity.

Investigators do not yet understand how smoking affects both the quality of sperm and the male's sexual habits, but they postulate that smoking might impair spermatogenesis secondary to various hormonal alternations caused by smoking. Alternatively, toxic substances from cigarette smoke may end up in the seminal plasma.

"The irony here is that it costs up to $40,000 in the US for couples seeking infertility treatment and they still smoke," said Zavos. It also does not help if the woman herself is a nonsmoker, he added, because if she co-habits with a smoker, "she's a smoker, too."

"The cheapest and most efficient way of improving infertility difficulties is to quit smoking," affirmed Zavos. "And if (couples) stop smoking immediately, that would probably be the first gesture (they could take) towards treatment for infertility."

Source: Reuters Health, 29 September 1999

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