Evaluating the effect of smoking and its cessation on semen parameters

Our primary aim was to investigate the reversibility of the negative impact of smoking on male fertility. Secondarily, we studied the effect of both time after smoking cessation as well as the smoking index on semen quality improvement. Our study included 60 participants who applied to a smoking cessation program. The volunteers started by completing a fertility background questionnaire. Two semen specimens, provided 2 weeks apart, were analyzed according to the WHO guidelines for each candidate on three different occasions. The first was right before smoking cessation, followed by the 2nd and 3rd at 3 and 6 months after stopping smoking. Semen quality was compared between the three occasions. The degree of change was correlated with the level of smoking. The nicotine level in urine was used for smoking cessation compliance monitoring during the study. Comparing semen quality on the three different occasions, we detected a significant improvement in semen volume (3.33 mL ± 1.07 vs 3.88 mL ± 0.80 vs 4.34 mL ± 0.67, P < 0.001), sperm concentration (14.77 million /ml ± 6.49 vs 17.71 million/ml ± 6.41 vs 19.27 million/ml ± 6.46, P < 0.001), total sperm count (49.33 million ±25.31 vs 70.16 million ±30.85 vs 84.01 million ±31.00, P < 0.001), progressive motility (20.7 vs 35.3% vs 42.28%, P < 0.001), total motility (41.48 vs 60.33% vs 67.67%, P < 0.001), and abnormal morphology (69.32 vs 50.88% vs 40.82%, P < 0.001). Improvement in all parameters was positively correlated to time after cessation. Higher smoking indices were related to higher levels of improvement in semen volume, sperm concentration, and total count (areas under the curve of 0.867, 0.852, and 0.863, respectively, P < 0.001 for each). Our conclusion was that the negative effect of smoking on semen quality is reversible. Smoking cessation has a time-dependent positive effect on main semen parameters, hence positive potential for fecundity improvement in men. Lay summary Extensive research efforts have always focused on the negative effects of smoking on male reproduction by comparing fertility in smokers versus non-smokers. There are very few studies looking at the effect of smoking cessation on male fertility. Our primary aim was to investigate whether the negative impact of smoking on male fertility was reversible. Our study included 60 participants who applied to a smoking cessation program. The volunteers started by completing a fertility background questionnaire. Each candidate provided two semen specimens 2 weeks apart, on three occasions. The first was right before smoking cessation, followed by the 2nd and 3rd at 3 and 6 months after stopping smoking. Semen quality was compared between the three occasions. The degree of change was correlated with smoking levels. We found the negative effects of smoking on semen are reversible.