With 40% of cases of infertility being due to problems in the male, this video of 5 common causes is very informative.  Although the causes are numerous, there are 5 causes that are most common, including:

1. Trauma to the testicles in early life.
2. Infections
3. Hormones
4. Genetics
5. Varicocles

Howcast.com created this video and offers more information regarding male infertility on their website.  Also on Howcast, information is available regarding other health issues including female infertility, how age affects fertility, and why there are more and more cases of infertility.  For those hoping to get pregnant, the information offered on this site is valuable indeed!