Infertility in a man can occur when chromosomes go through balanced changes leading to azoospermia or oligozoospermia.
To clarify the causes of infertility before artificial insemination takes place, it is therefore advisable to carry out a chromosome analysis. For this purpose about 5ml of heparinise venous blood is needed. The result of chromosome analysis can assist in the decision of whether to proceed with artificial reproduction.

Some men carry an additional X-chromosome in their cell nuclei. Boys with a karyotype 47.XXY (Klinefelter syndrome) can suffer from a slow psychomotor development after birth. They can also grow quicker than other children of the same age and tend to be relatively tall as adults. Men with Klinefelter syndrome feel like other men as their sexual identity was imprinted through their Y chromosome from the beginning; however, the changed chromosome set disrupts sperm production. These men have a azoospermia and cannot produce children. In some cases this can be solved with the help of artificial reproduction.