Recurrent miscarriages and implantation failures

Recurrent miscarriages and implantation failures

Recurrent miscarriages are considered when at least two pregnancies have ended in miscarriage, whereas we speak of implantation failure when a patient has not achieved pregnancy after several good-quality embryo transfers.

We believe recurrent miscarriages and implantation failures result in the same conclusion. In the event of implantation failure, abnormalities are produced before the embryo has started to develop inside the uterus.

Recurrent miscarriages

You can find below the most common causes of recurrent miscarriages.

Most common causes

Genetic causes

This is the most common cause for recurrent miscarriages and implantation failures. Genetic abnormalities of the embryos may lead to them not implanting or the pregnancy ending in miscarriage.

Most of the embryos that have genetic abnormalities can develop normally in the laboratory, which means preimplantation genetic diagnosis is the only way to identify them.

Uterine causes

The most important uterine causes for recurrent miscarriages and implantation failures are:

  • Chronic endometrial infections that are asymptomatic.
  • Uterine cavity abnormalities such as polyps, myomas, divisions or adhesions.
  • Endometrial receptivity alterations due to abnormalities in the implantation window. This window is the period of time in which the endometrium allows an embryo to implant and has a duration of 2-6 days, due to progesterone.
Antiphospholipid syndrome
With antiphospholipid syndrome, the mother produces antibodies that can affect the placenta through thromboembolic phenomena, impeding the trophoblast invasion of the tissue of the uterus at the time the embryo is implanted, bringing about pregnancy loss.
Coagulation disorders
Thrombophilia increases the risk of thrombosis. This thrombosis affects the placentation process during pregnancy, which can end in miscarriage. Occasionally, these abnormalities are produced prematurely, so causing the embryo implantation to be ineffective.
Immunologic and endocrine causes
In order for the pregnancy to develop, the “immunological tolerance” phenomenon needs to occur, which allows a woman to carry a baby for 9 months in her womb without her body considering it a foreign body and attacking it. Any abnormality in the woman’s immunological reaction could cause the embryo to not implant or end in miscarriage.
Recurrent miscarriages and implantation failures

Tests for examining recurrent miscarriages

Examination of recurrent miscarriages and implantation failures must include the following diagnostic tests.

Diagnostic tests
Genetic testing of the couple
  • Karyotyping: the aim is to determine the couple’s chromosome formula. The normal karyotype of a woman is 46,XX and that of a man is 46,XY.
  • Chromosomal study of the spermatozoa: FISH technique can be used to determine whether the percentage of sperm with chromosomal alterations is significantly increased regarding the fertile population.
  • Study of sperm DNA fragmentation: the Comet technique can be used to determine if the DNA contained in the sperm head is damaged and whether this damage affects one of the two DNA strands or both. Poorer embryonic quality and an increased risk of miscarriage can be the result of increased DNA damage.

Allows us to study the uterine cavity to eliminate malformations, polyps, myomas or adhesions.

Endometrial study
  • Endometrial receptivity: by performing an endometrial biopsy we can evaluate the window of implantation of the endometrium and confirm that it is open when we perform the embryo transfer. Such tests are available on the market known as ERA and Matricelab®.
  • Study of the microbiome: by endometrial biopsy we can confirm whether the endometrial lactobacilli population is correct and eliminate chronic asymptomatic infections (endometritis) that can interfere with proper implantation, increasing the risk of miscarriage. Its commercial name is EMMA/ALICE®.
  • Endometrial cultures: these are used as a complement to microbiome studies in order to select the appropriate antibiotic for correct treatment in the event of a positive result.
Antiphospholipid syndrome
Consists in the study of various antibodies that increase the risk of miscarriage, such as lupus anticoagulant, anticardiolipins or beta2glycoproteins.
This consists in the study of various alterations in coagulation factors that may increase the risk of miscarriage. These studies can be carried out on blood or saliva.
Hormone tests

Tests on the ovarian reserve may alert us to an egg problem.

Thyroid function tests includes examining the TSH and T4L hormones.

Recurrent miscarriage treatment

Miscarriage treatment is determined by their cause. The cause of recurrent miscarriages occasionally cannot be diagnosed and, in that case, the indicated treatment is In Vitro fertilisation with Preimplantation genetic diagnosis. This technique allows us to examine the embryo chromosomes and ensure that we will transfer normal embryos.

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