Semen quality and cigarette smoking in a cohort of healthy fertile men.

BACKGROUND

Numerous health effects of smoking are well-known; associations with semen quality are uncertain. Most previous studies did not adjust for potential confounders and had limited information on age at smoking initiation or smoking cessation.

METHODS

We investigated 1,631 healthy fertile men in the Nanjing Medical University Longitudinal Investigation of Fertility and the Environment (NMU-LIFE) study. Relationships were examined using multivariable linear regression controlling for potential covariates.

RESULTS

We found a significant decrease in semen volume ( = -0.10, = 0.001) and total sperm count ( = -0.42, = 0.037), and significant increase in total motility ( = 6.02, = 0.037) and progressive motility ( = 5.52, = 0.037) in ever smokers of pack-years ≥10 compared with never smokers. We observed an inverse dose-dependent relation between smoking pack-years and semen volume ( < 0.001) and total sperm count ( = 0.010) and a positive dose-dependent relation between smoking pack-years and both total motility and progressive motility ( = 0.042 and 0.048, respectively). No significant differences in semen quality were detected among ever smokers with different ages at smoking initiation nor in former smokers compared with never smokers.

CONCLUSIONS

Cigarette smoking was associated with lower semen volume and total sperm count and higher sperm motility. Smoking cessation might have a restorative effect on semen quality. This finding has important implications for public health research and for understanding the development of abnormal semen quality.