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.

Diagnostic tests

Genetic testing of the couple

Karyotypes: it determines the couple’s chromosomal formula. A normal female karyotype is 46XX and for a male, 46XY.

Chromosome analysis of sperm: through the FISH technique, an examination of the 5 chromosomes whose abnormalities are frequently related to miscarriages and implantation failures can be performed.

Hysteroscopy and endometrial test

A hysteroscopy allows us to rule out uterine cavity abnormalities.

An endometrial test consists of performing an endometrial biopsy at a certain point during the cycle in which we can perform the following tests:

• Endometrial receptivity: examines the implantation window to confirm that the endometrium is receptive when the embryo is transferred.
• Endometrial cultures: to rule out asymptomatic endometrial infections.

Antiphospholipid antibodies

This includes an examination of Lupus, anticardiolipin and B2- Glycoprotein anticoagulant antibodies.

Thrombophilia

This consists of examining the factors involved in the coagulation mechanism. It can be performed by blood test or saliva sample.

Hormone tests

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

Thyroid function tests includes examining the TSH and T4L hormones.