Miscarriages are very common. The definition of Recurrent Miscarriage has more to do with the likelihood of finding a cause that we can treat than any actual number. It is therefore statistically quite likely that anyone might suffer from more than one.
Some years ago, when very few causes were known, it was normal to avoid investigation until six miscarriages had occurred. Now we will usually consider investigating the couple after two consecutive similar occurrences. This happens for approximately 10 – 15%% of couples trying for a baby.
Why does miscarriage happen?
Most miscarriages represent quality control. The embryo must reach a series of milestones and if it fails, it is ejected. However there are a number of maternal diseases or conditions that are known to cause miscarriage, as per below:
Diseases such as Smallpox or Brucella Abortus (practically never seen these days) were a major issue in agricultural societies. There is little or no evidence that infection is a major cause of recurrent abortion. Acute infections of many types will cause abortion (malaria, rubella, listeria etc.) but the body will usually develop immunity preventing recurrence due to the same cause. Infection is not generally investigated in depth unless there are indicative features such as exposure or symptoms.
“Mistakes” made in copying genes during production of egg or sperm. These mistakes range from extra chromosomes: three rather than the normal pair of the number 21 chromosome (trisomy 21) produces Down’s Syndrome. . . . through rearrangements of parts of chromosomes (which might not have any clinical effect and in fact be present in either parent)… to mutations of individual genes (some of which we now recognize and can test for). Genetic abnormalities are found in about 5% of recurrent abortion.
Gross chromosomal abnormalities may be found on examination of the fetal material after evacuation of retained products of conception (ERPC) or examination of blood tests from both parents. Genetic problems, that is those arising from individual gene mutations, may be suggested and investigated by discussion with a specialist geneticist. There is no treatment other than prenatal diagnosis and therapeutic abortion.
In order to conceive at all, the mother must have pretty normal uterus, Fallopian tubes and ovaries. Abnormality of the cavity of the womb may, however, interfere with implantation (settling into the lining of the womb by the embryo). A polyp may act a bit like a contraceptive coil.
A septum in the womb (a wall down the middle like the nasal septum in the nose) may have poor blood supply and not nourish the embryo properly. A fibroid under the lining might do the same. A bicornuate uterus, so called because it has two ‘horns’, may be present. The womb is formed from two tubes which sometimes do not fuse properly. This typically produces a picture of pregnancies that last a bit longer each time as the ‘horn’ of the uterus is stretched a bit more with each pregnancy.
Anatomical causes may be investigated with a simple examination in Crete Fertility Centre (an open cervix suggests that it might be incompetent). An Hystero-salpingogram (HSG) is an X-Ray examination which can show “funneling” of the cervix suggesting incompetence or a septate (with a septum) or bicornuate uterine cavity. It is wise also to examine the uterine cavity with an Hysteroscope as we do in C.F.C..
A woman needs all her control mechanisms working properly. Any endocrine (hormone) disease may produce miscarriage. Usually it will be severe enough to diagnose and will commonly be associated with failure to conceive. Diabetes mellitus may not have been diagnosed. Poor control can give a raised rate of miscarriage and fetal malformation. Good control of blood sugar before and in early pregnancy can bring this back to normal. Hormonal problems may be diagnosed with blood tests and treated appropriately, PCOS (Polycystic Ovary Syndrome).
Certain diseases in which the body’s defense mechanisms attack our own bodies are called ‘auto-immune’. We find some evidence of autoimmune disease in about 10% of recurrent abortion. “Rhesus auto-immunization” is not strictly an autoimmune disease as the rhesus negative women develops antibodies to rhesus positive blood which then attack her fetus (not herself). It usually presents as a problem of late pregnancy and will normally have been recognized before it becomes a cause of recurrent miscarriage.
This means literally “a predisposition for clotting the blood” or an increased risk of clotting. The risk of deep vein thrombosis increases a thousand fold in normal pregnancy. Factor V Leiden mutation is a gene that can be inherited from either of the woman’s parents and makes her much more at risk of miscarriage and deep vein thrombosis.
Auto-antibody and Thrombophilia screening blood tests may diagnose Auto-immune disease or Thrombophilia. Treatment involves aspirin, low molecular weight heparin and occasionally steroids.