1. Introduction
nfertility is one of the common problems affecting about %15 of couples [1]. The major cause of infertility in 30% of couples is the sperm quality as a male factor [2]. The relationship between smoking and reproductive disorders is still contradictory [3, 4]. Many studies have associated smoking with detrimental effects on semen parameters such as semen volume, sperm count, motility and morphology [2, 5, 6], whereas others failed to find a significant correlation between sperm analysis and smoking [4, 7, 8].
This retrospective study aims to evaluate the relationship of sperm parameters with smoking in men with idiopathic infertility.
2. Materials and Methods
This is a retrospective study. First, ethical approval was obtained from the Ethical Committee of Guilan University of Medical Sciences, and the confidentiality of patient information was observed. Then, the medical records of 4443 infertile men referred to infertility clinics in Rasht, north of Iran during 2001-2010 were evaluated and 2699 men were excluded from study because due to having diseases such as varicocele, vas deferens, hyperthyroidism, and diabetes mellitus. Finally, 1744 men aged 22-75 years with at least one year history of idiopathic infertility were included in the study. In this study, men considered infertile if they did not achieve having children after one year of sexual intercourse without using contraceptive methods. The subjects were divided into two groups according to their cigarette smoking habit: A: Smokers who smoke five cigarettes a day for at least 5 years; and B: Non-smokers who had never smoked before. Then, the data from semen analysis taken from the average results of two or more semen tests, were extracted from patients’ medical files and undergone statistical analysis. All statistical analyses were performed in SPSS V. 19 software. Data were described using mean and standard deviation. Kolmogorov Smirnov’s test was used to examine the data distribution normality. Independent t-test and chi-square test were used to compare the study variables between study groups in the case of normal data distribution. Due to normality of data distribution, no non-parametric test was used. For all analyses, P<0.05 was considered as statistically significance level.
3. Results
In this study, the semen parameters of 1744 infertile men were evaluated. 379 men were smoker (21.7%) and 1365 men were non-smoker (78.3%). The age of subjects ranged 22-75 years with a Mean±SD age of 37.3±7.21 years, while 75% were under 41 years of age. There was no significant difference in age between smokers (37.65±7.69) and non-smokers (36.87±7.06) (P=0.061). A total of 1380 men (79.1%) had abnormal sperm motility; 364 (20.9%), normal sperm motility; 138 (7.9%), abnormally-shaped sperm; 1606 (92.1%), normal-shaped sperm; 397 (22.8%), abnormal semen volume; 1374 (77.2%), normal semen volume; 574 (32.9%), abnormal sperm count; and 1170 (67.1%), normal sperm count. 
There was a significant difference in semen volume between smokers (28.5%) and non-smokers (21.0%), and smoking significantly decreased semen volume (P=0.002). There was also a significant difference in sperm motility between smokers (74.4%) and non-smokers (80.6%), and smoking could significantly reduce sperm motility (P=0.009). In order to control the effects of smoking on sperm motility, the relationship between smoking and sperm motility was first analyzed separately for men with abnormal and normal semen volumes. Although there was a close relationship between smoking and semen volume in group with normal semen motility (P=0.058), but analysis of the association of smoking with sperm motility between men with abnormal and normal semen volume was not statistically significant. There was no significant difference in sperm count between smokers (34%) and non-smokers (32.5%). Hence, there was no significant relation between smoking and sperm count (P=0.561). The Mean±SD values of semen morphology did not show any significant difference between smokers (62.4±28.1) and non-smokers (61.5±27.9) (P=0.998). The non-signifanct results may be due to the type of study population in our study where heavy smokers were not separated from mild smokers.
4. Conclusion
It seems that cigarette smoking has detrimental effects on standard sperm parameters (semen volume, sperm count, sperm motility, semen morphology). Physicians should advise infertile smoker men to stop smoking cigarette. Further study is recommended to elucidate the underlying mechanism of sperm damage caused by cigarette smoking.

Ethical Considerations
Compliance with ethical guidelines
All procedures performed in this study involving human participants were in accordance with the ethical standards of the Ethics Committee of Guilan University of Medical Sciences and with the Helsinki Declaration. Informed consent was obtained from all individual participants involved in the study.

Funding
This article was extracted from Mahsa the PhD. dissertation of third author, Urology Research Center, School of Medicine, Guilan University of Medical Sciences, Rasht, and this article was financially supported by Urology Research Center, Guilan University of Medical Sciences.

Authors' contributions
Conceptualization, supervision: Gholam Reza Mokhtari; Methodology: Atefeh Ghanbari; Investigation: Gholam Reza Mokhtari, Mahsa Zeinali Moghaddam, Samaneh Esmaeili; Writing – original draft: Samaneh Esmaeili; Writing – review & editing: Gholam Reza Mokhtari, Mahsa Zeinali Moghaddam, Samaneh Esmaeili.

Conflicts of interest
The authors declare that they have no conflicts of interest.


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