There are some areas where the father's health before pregnancy is important. When the mother-to-be is looking at her lifestyle and changes she will make to ensure a healthy baby, the couple should be discussing how lifestyle choices for the father-to-be would also improve chances of a successful conception.
For example, research is beginning to show that the use of illicit drugs or large amounts of alcohol used by the father before conception could prevent pregnancy or lead to a poor pregnancy outcome. The mechanisms are not clear, but drugs can possibly damage sperm as well as reduce their number. The drugs can alter testicular function, reduce testosterone levels and can be excreted in the semen. 

(Adapted from: Eisenberg, Murkoff and Hathaway. " What to Expect When you are Expecting" 2002)

For more information, check out "For men only: we are pregnant" on Best Start's, Your Health Before Pregnancy webpage.