What causes male fertility problems?

Various medical issues can contribute to male fertility problems, including:

• A problem in the hypothalamus or the pituitary gland — parts of the brain that signal the testicles to produce testosterone and sperm (secondary hypogonadism)
• Testicular disease
• Sperm transport disorders

Age can also play a role. The ability of sperm to move and the proportion of normal sperm tend to decrease with age, affecting fertility, especially after age 50.