Background & Objectives: Pregnancy is one of the most sensitive periods of lifetime and married life and sexuality may bring about numerous physical and psychological changes. Lack of attention to sexual matters during pregnancy may cause sexual dysfunction in each of couples. The aim of this study was identifying male sexual behavior and its relevant factors during the partner’s pregnancy.

 Methods: This was a descriptive-analytical study in which 350 men, whose wives were pregnant, were selected in two stratified stages. The instrument for data collection was Arizona Sexual Experiences Scale- male questionnaire. All data were analyzed by SPSS11.5. Descriptive information was used for describing the frequencies and also the x2 test was used for determining relation ship among variables.

 Results: The findings revealed that 21.3% of men in the first trimester, 19.3 in the second and 28.3 in the third trimester had sexual dysfunction. In each trimester, inability to reach orgasm was the most common sexual dysfunction in men. Frequency of vaginal coitus decreased in 64.9% of men and in 46.6 % of them fear from risk for fetus health during vaginal coitus was the essential reason for this reduction. There were significant differences between sexual dysfunction and fear from risk for fetus health and guilt feeling of sexual activity. Therefore decreased vaginal coitus caused sexual dysfunction.

  Conclusion: As men’s knowledge and attitudes about sexuality affect their sexual behavior during pregnancy it is crucial to provide proper consultation regarding sexual relations in prenatal care services.