Causes of recurrent miscarriage

Recurrent miscarriage

Causes of recurrent miscarriage



Recurrent miscarriage is considered to be the loss of two consecutive pregnancies or more than two alternate pregnancies. It is a fertility problem that affects about 5% of women in childbearing age.


Recurrent miscarriage can be due to multiple causes and factors. Only a good diagnosis can lead us to administer the most appropriate treatment for the woman who seeks to become pregnant.


Types of causes of recurrent miscarriage


Genetic factor (H3)


Around 50-80% of spontaneous losses in the first trimester of pregnancy is caused by an abnormal number of chromosomes. Although these chromosomal abnormalities occur randomly during fertilization, they become more common in women of increased reproductive age.

In some couples with recurrent miscarriages, one of the members is carrier of an abnormality on the structure of his / her chromosomes, such as translocations or inversions. Carriers usually do not have any physical signs or symptoms, but they are at risk of producing abnormal embryo that often leads to miscarriage.


The best way to determine if the cause of the miscarriage is genetic (spontaneous or related to an abnormality in the parent’s chromosomes), is through the study of the karyotype of fetal tissue, as well as the karyotype in blood of both parents. If one member of the pair is carrier of an abnormality, In Vitro Fertilization cycle with special genetic analysis called Preimplantation Genetic Testing (PGT-SR) can be done to select unaffected embryos.


Uterine anatomical lteration 


An abnormality in the uterus as well as a pelvic adhesion could be the cause of a repeated abortion. In the second case, it can be caused by an endometriosis, the extraction of myomas or septa, or a cervical insufficiency, which is why the uterus is not able to maintain the fetus. However, the good news is that the probability of eradicating a uterine anatomical alteration is very high.


Endocrine causes 


Some of the most common are problems of overweight, hypothyroidism and other conditions linked to the thyroid gland, polycystic ovarian syndrome (PCOS) or luteal insufficiency.




Thrombophilias are caused by an instability in blood coagulation, and are the pathology that predisposes women to thrombosis. The formation of a thrombus can be one of the causes that produces repeated abortions.


Depending on the time of appearance, there are two types:

  • Congenital thrombophilia, in the case of those who are already born with the disease
  • Acquired thrombophilia, for those who suffer from it later or from a certain moment in their lives.


Immunological causes 


It is possible that the recurrent miscarriage was caused by a failure of the mother’s immune system to reject the paternal antigens expressed by the fetus. If the organism, instead of protecting the embryo, reacts against it, an interruption of the pregnancy or abortion can occur. It is considered that it may be the cause behind the cases in which the abortion occurs more than five times.


Environmental factors

Exposure to certain chemicals, drugs, x-rays, excess use of alcohol or smoking.


What are the ways to diagnose?


The possibilities are diverse to find the origin of repeated abortion in a couple. The most efficient and commonly performed tests are the following:


  • Karyotype of the two members of the couple to detect alterations in their chromosomes.
  • Imaging tests of the woman’s uterine cavity to rule out abnormalities.
  • Analytical to rule out endocrine, immunological and thrombophilic factors.
  • Hormone study of women.
  • Seminal analysis of man.


In any case, it will be a fertility professional who determines the best alternative and diagnostic method. It is important that each case is carefully analyzed, not only at the level of physical health, but also the emotional health of the couple that seeks to conceive.


PGDlabs can offer you the most suitable genetic test related to recurrent miscarriages: male and female karyotyping, thrombophilia genetic testing and / or genetic analysis of products of conception. For carriers of an abnormality on the structure of his / her chromosomes, Preimplantation Genetic Testing (PGT-SR) in collaboration with an Assisted Reproduction Clinic can be offered, after appropriate genetic counseling of the couple.


If you have any questions or need advice, we remain at your disposal.