Further evidence that cigarette smoking may be detrimental to male fertility.

Smoking can have adverse effect on semen quality, and may consequently cause a reduction in male fertility, research confirms.

"Many studies have suggested that cigarette smoking is associated with altered semen quality, but conclusions about the extent of the deleterious effects vary widely," write Dr. Nick Bersinger (University of Berne, Switzerland) and co-authors. Postulating small study sizes and differences in the thresholds used to define smokers and non-smokers could explain this variation, the researchers studied a large group of men in whom the definition of "smokers" was strict (1 or more cigarette per day).

The study included 655 smoking and 1,131 non-smoking men, who completed a questionnaire including questions on age, alcohol use, and reproductive history. Semen samples were collected for analysis from each participant.

Cigarette smoking was associated with a significant decrease in sperm density, sperm count, number of motile sperm, and citrate concentration. Sperm morphology was also adversely affected by smoking.

The researchers conclude that, while sperm variables in smokers may remain in the normal range, a "clear negative trend is observed." Accordingly, "men with borderline semen quality who wish to have children should especially benefit from quitting smoking," they suggest.

Source: Fertility and Sterility 2003; 79: 287-91, 3 March 2003