There are three main reasons for problems with sperm. They are: function, delivery and production.
Sperm can have an unnatural shape and movement that would produce problems for fertilization. Clearly if the sperm have mobility problems they will have difficulty even reaching the egg. Any unnatural shape of the sperm also promotes to difficulty with mobility.
Normally a man produces roughly 20 million sperm per milliliter of semen. If the test discloses that a man has 10 million or fewer, than it would be classified as having a low sperm count. There are a lot of reasons for a low sperm count. When a man has less than 5 million sperm per milliliter of semen, than genetic causes are observed.
Reasons for low sperm count:
Diseases like Varicocele, which prevents the testicle from cooling. When temperature is too high sperm cannot survive. An undescended testicle happens when one or both of the male testicles fail to fall from the abdomen into the scrotum during fetal development. This causes problems in sperm production because the sperm are displayed to higher body temperature in the abdomen.
Other causes of low sperm count are: abnormal hypothalamus, pituitary glands or disorders of the testicles. There is a disorder of the sex chromosomes that can cause abnormal development of the testicles which results in a lower than normal level of testosterone.
Males who contract certain infections can also have an adverse affect on their sperm count. Scarring happens during the course of such diseases as chlamydia and gonorrhea can cause block the passage of sperm. When males come down with the disease mumps past childhood, they can experience an inflammation of their testicles that may result in lower sperm counts or impaired sperm.
Delivery problems are classified as when the man has difficulty getting the sperm from his penis into the woman’s vagina.