INFERTILITY DIAGNOSIS Article · 28 June 2022

Genetic testing – the first step to know the cause of a miscarriage!

A woman after a miscarriage is most often referred for hormonal, anatomical or immunological tests. Genetic diagnosis is usually left at the very end when the other tests show nothing worrying. Statistics show, however, that approximately 70% of all miscarriages in early pregnancy are due to genetic disorders.

genetic testing

A woman after a miscarriage is most often referred for hormonal, anatomical or immunological tests. Genetic diagnosis is usually left at the very end when the other tests show nothing worrying. Statistics show, however, that approximately 70% of all miscarriages in early pregnancy are due to genetic disorders.


Therefore, it is more and more often said that the first step on the way to finding out the cause of miscarriage should be DNA tests – performed on the fetus and both parents. The results of the genetic tests should be discussed with your geneticist or reproductive medicine doctor.


Random changes in genetic material are usually responsible for miscarriage. It is nature that determines that the fetus is burdened with them. These changes are usually not inherited, but they can stop the child’s development and cause fetal death. Although the risk that the baby will be burdened with them in the next pregnancy is small, it is worth doing genetic tests of the miscarried fetus and finding out about the presence of possible disorders in the DNA.


The sample for genetic testing after miscarriage is usually a chorionic villus fragment. The doctor places it in saline immediately after cthe curettement. If the chorion is unsuccessful, a paraffin block can be used for analysis.


Analysis of the number and structure of chromosomes


Genetic testing of miscarriage allows us to find out the causes of pregnancy loss. The most common are: the presence of an additional chromosome 21 (Down syndrome), the presence of an additional chromosome 18 (Edwards’ syndrome), an additional chromosome 13 (Patau), or the absence of one X chromosome (Turner syndrome).


In this study, the individual chromosomes of the child are analyzed – their number and structure are checked. In this way the child’s karyotype is examined. However, this is not all. When examining material from a miscarriage, it can also be determined whether the child was male or female. With the help of ultrasound, the doctor is able to determine the sex of the baby only about 16 weeks of pregnancy. However, for genetic testing, pregnancy age is not of the slightest importance, since sex is a characteristic given at the time the egg connects with the sperm.


Parent, check your chromosomes!


Statistically, even 2 – 6% of parents are carriers of chromosome aberrations. The presence of abnormalities in the structure or number of chromosomes is associated with a greater risk of pregnancy failure, including habitual miscarriages. Such a parent has no visible symptoms that would suggest that their genetic material has errors. The only thing that can disturb them is repeated miscarriages.


If one of the parents is a carrier of chromosomal aberration, there is a danger that the next pregnancy will also result in miscarriage (changes of this type are hereditary). The risk of re-miscarriage, having information about the type of genetic change, will only be determined by a geneticist. If necessary, he may propose to a couple prenatal tests or preimplantation diagnostics (PGD).


Karyotype test


It is worth adding that the presence of aberrations in chromosomes does not always have to lead to pregnancy loss. The fact that the couple already has healthy offspring does not mean that the genetic defect did not contribute to the miscarriage. In the case of a chromosomal aberration in one of the parents, the karyotype of healthy children should also be examined to see if they are carriers of the change occurring in the parent.

Parental karyotype is a completely non-invasive study. Partners donate only a few milliliters of peripheral blood.


Habitual miscarriages and thrombophilia


After a miscarriage, a woman should make sure that there is no innate propensity for thrombosis or congenital thrombophilia. It is conducive to the development of this dangerous disease. Congenital thrombophilia itself is asymptomatic. A woman most often reports to a doctor when she develops the first signs of thrombosis, i.e. redness and swelling of one of the lower limbs. Congenital thrombophilia, although not visible to the naked eye, can have serious consequences. In addition to the mentioned thrombosis, it also causes obstetric complications, including in the form of habitual miscarriages.


Congenital thrombophilia is diagnosed today using genetic tests that identify specific mutations in DNA, primarily the mutation of factor V Leiden and the prothrombin gene.


The first step – genetic testing


The result of a genetic test can really decide about the course of all miscarriage diagnostics, because genetic disorders are responsible for the majority of miscarriages in early pregnancy, and the diagnostics is doften finished after DNA tests. However, if it is not possible to determine the direct cause of miscarriage with their help, it means that it should be looked elsewhere.


Therefore, miscarriage diagnosis should begin with genetic testing. This does not mean, however, that it should end with them. The reason for losing pregnancy may not necessarily be in genetics. Miscarriage can also occur as a result of hormonal disorders, anatomical defects of the reproductive organs, infections (cytomegaly, toxoplasmosis, rubella, chlamydia trachomatis). When looking for the cause of miscarriage, it is worth excluding all these factors, especially if the first genetic tests do not provide an unambiguous answer.


Psychological comfort


It is certainly easier for parents to come to terms with the loss of a child when they know that the miscarriage was not the result of their neglect, but a matter of case that they could not protect themselves in any way. By determining the child’s gender through genetic testing, they can also give the child a name and apply for the rights they are entitled to after a miscarriage (funeral grant, maternity leave).


And finally, knowing that the cause of the miscarriage was a genetic defect, the doctor will be able to estimate the risk of the miscarriage recurring in subsequent pregnancies. It should be emphasized that miscarriage is usually a one-off event. Women who lose pregnancy usually give birth later to healthy children and their pregnancy goes without complications.

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