Every living organism has a specific set of chromosomes known as the karyotype. A karyotype consists of 46 chromosomes, with 22 pairs of autosomes and one pair of sex chromosomes.

Women have two X chromosomes (karyotype: 46, XX), while men have one X chromosome and one Y chromosome (karyotype: 46, XY).

Each chromosome contains genes with hereditary information. A karytype can be analysed using cytogenetic and molecular genetic methods.

The maldistribution of chromosomes in all cells or in just some (mosaicism) can also have a considerable impact on fertility. Also changes in individual chromosomes may result in infertility, reduced fertility or miscarriages.

There are many possible reasons for repeated miscarriage, but about 85 % of all miscarriages are attributable to chromosomal anomalies of the embryo. However, for patients who experience multiple miscarriages after the detection of a foetal heartbeat, the cause is more likely to be a blood clotting disorder (thrombophilia), a hormonal imbalance or a pathological change.

Genetic counselling

Genetic counselling should be used in cases such as the following:

• if a genetic disorder is presumed to be present
• if one or both partners are known to be carriers of a genetic disorder
• if a possible genetic disorder has occurred in family members
• if a couple has already had one child with a genetic disorder
• if the partners are related
• if the parents are older when they decide to have children
• in case of multiple miscarriages with no known cause
• in case of fertility problems