Sperm Abnormalities

• Sperm abnormalities include low sperm count, slow-moving sperm or oddly shaped sperm. Sperm abnormalities can be caused by genetic disorders or hormone imbalances.
  
  

Retrograde Ejaculation

• Retrograde ejaculation occurs when the ejaculate goes back into the bladder instead of out the urethra. This can be caused by diseases such as multiple sclerosis or a recent bladder surgery.
  
  

Environmental Factors

• Exposure to elements of the environment such as heat and chemicals can cause sterility in males. Using saunas frequently can temporarily lower the sperm count as well as wearing tight clothing.
  
  

Hormonal Deficiencies

• Hypogonadism is a general term used to describe a lack of a gonadotropin-releasing hormone, which controls the release of testosterone. Low levels of testosterone can result in defective sperm.
  
  

Genetic Disorders

• Genetic disorders such as cystic fibrosis can result in missing or blocked vas deferens, also known as the tubes that transport the sperm.