Three or more miscarriages that occur before 24 weeks of pregnancy are considered repeated. Approximately 1 in 100 couples trying to get pregnant will face repeated miscarriages.
In less than 50% of these couples, a specific cause will be identified, albeit the majority of the rest of the couples without diagnosis will be able to have children eventually.
There are several factors related to repeated miscarriages:
- Age: The chances of a miscarriage increase as a woman gets older. In women over 40, more than 1 in every 2 pregnancies will result in miscarriage.
- Antiphospholipid syndrome (APS): This is a disorder characterised by a tendency of the blood to hyper-coagulate.
- Genetic factors: In 2-5% of couples with repeated miscarriages, one of the partners has a chromosomal anomaly, even though he/she presents normally.
- Cervical insufficiency: This usually pertains to miscarriages that occur between 14 and 23 weeks. It is difficult to diagnose, but it is suspected when there is a previous premature birth.
- Infections: The role of infection in repeated miscarriages is unclear.
- Thrombophilia: Hereditary disorders with a tendency for the blood to hyper-coagulate.
- Anatomical abnormalities of the uterus: Such as bicornuate uterus or unicornuate uterus. Uterine septum is a less common cause of miscarriage, especially if it is small.
- Type I diabetes and thyroid disorders: These conditions do not cause miscarriages if they are regulated.
- Natural Killer (NK) Cells: To protect the embryo, there is partial inhibition of special cells in the mother’s immune system; the purpose of these cells is to react adversely to any foreign intruder and they are used by the body as a defence. Knowing the functional status of NK cells, i.e. if they have a harmful effect on the foetus, is important in miscarriages or failed IVF attempts despite ideal pregnancy prospects.
- Catching antibodies (APCA): Tissue data (which comes from the embryo’s father) are genetically coded and determine a genetic site, the ccHLA-G antigen in the incipient placenta. The production of anti-parietal cell antibodies by the mother is important for the survival of the newly formed placenta and consequently for the pregnancy.
- Immunological factors: In some couples, the immunological link to the embryo appears to be unusual.
- Excessive alcohol consumption
There are tests to investigate all of these factors of repeated miscarriages, and depending on the case, treatment may be with medication or changes in how the case is handled (genetic counselling, egg donation, sperm donation, surrogacy, adoption). In cases where a cause is not identified, treatment is usually empirical.
Certainly, psychological support is of primary importance and must not be disregarded by these couples before any other intervention.