At least 60% of first trimester miscarriages are due to a chromosome abnormality, the majority of which are not inherited. Karyotyping the miscarriage material will be able to give an answer for the pregnancy loss in 60% of cases. Follow up genetic testing of the parents will be indicated in a small number of these cases.
Miscarriage material can be tested by conventional karyotype and if this fails then another test called a microarray can be considered. Conventional karyotyping helps in cases where there is a balanced structural rearrangement (which an array cannot detect) as well as extra or missing chromosomal material.