This is the numerical and structural study of all the chromosomes in the cell. A cause of infertility in women and men can be determined by an abnormality at the level of the karyotype, either numerical (sex chromosomes) or structural (balanced translocations or other abnormalities that do not involve loss or gain of genetic material). A karyotype examination is recommended in cases of infertility to determine whether the couple is at risk of giving birth to a child with malformations and severe psychomotor retardation.