Care programme for recurrent miscarriages

Maybe you've experienced this? Extremely happy with the confirmation of pregnancy, and then bitter disappointment: the pregnancy is not progressing or ends in a miscarriage.
Unfortunately, you are not alone: many pregnancies end prematurely. Depending on when this happens, it is referred to as a miscarriage or not.

See “Recurrent miscarriage?” We also talk about the possible causes.

Consultations - Where and when?

By appointment, On Monday or Thursday
Contact us at the CRG contact centre, by mail or telephone

What is a (recurrent) miscarriage?

Humans are not the most fertile creatures because of all fertilisations at least half is lost. In most cases this is because the fertilised egg does not implant: in this case we don't talk of a (starting) pregnancy.
If the fertilised egg does implant in the uterus, pregnancy hormone is produced. This allows you to determine you are indeed pregnant. But even then many pregnancies don't progress.
  • If the development stops very quickly, we call it a biochemical pregnancy. There is an increase of the pregnancy hormone in the blood, but no ultrasound observation to confirm the pregnancy.
  • In other cases an amniotic sac develops, but no yolk sac and embryonic pool. In medical terms this is referred to as a blighted ovum (wind egg).
  • We only talk of a ‘miscarriage’ when on the ultrasound an embryo with heart activity was visible and the pregnancy subsequently no longer progresses.
Generally, a miscarriage is seen as a natural selection mechanism, because the cause is usually a genetic or development abnormality of the embryo or a wrong implantation in the uterus.

How great is the risk of miscarriage?
Of all pregnancies which show a positive heart action at seven weeks:
  • 15% is still lost;
  • 80% occur during the first 12 weeks of pregnancy.
The further a pregnancy progresses, the smaller the chance of miscarriage. After twelve weeks, the chance is only about 1%.
The risk is age-related:
  • a 20 year old woman has a 12% risk, 
  • while a woman over 40 has a 26% risk.
This is logical because the quality of a woman's eggs diminishes with age and the chance of genetic (chromosomal) abnormalities of the embryo increases.

What is meant by recurrent miscarriage and how often does it happen?
Recurrent miscarriage is a succession of at least two miscarriages without there being a normal pregnancy in between. Of all pregnant women:
  • five percent experiences two consecutive miscarriages; and
  • two percent even has three consecutive miscarriages.

 

What is the risk of a new miscarriage (after the previous one)?
  • The risk of another miscarriage after the first is 17%, i.e. the risk has hardly increased.
  • After two consecutive miscarriages the risk does increase, to 25%,
  • after three consecutive miscarriages the risk increases to 30% and more.

In most cases a reason for the recurrent miscarriage cannot be identified. But that doesn't mean we don't look for one: see 'possible causes' (below) for aspects we could examine.

Possible causes of recurrent miscarriage
To date we have not found one particular cause for (recurrent) miscarriage. Probably various factors play a role, both in the embryo and the mother.

Genetic factors
Environmental factors
Hormonal factors
Anatomical abnormalities
Viral infections and immunological causes

Genetic factors     

We know that a large number of human embryos show some sort of genetic abnormality. Particularly when the woman is older and the egg quality decreases, there is a higher risk of chromosomal abnormalities. This is why (recurrent) miscarriage is more frequent in an older population.

A couple can have a large proportion of abnormal embryos as a result of a genetic abnormality in the DNA. However, this diagnosis is not very frequent, only in two to five percent of the couples who had three miscarriages.
Some researchers believe that even in this situation embryonic genetics is not the true cause of the miscarriage. The problem lies in the lining of the womb, which is not selective enough. It should have the capacity to recognise abnormal embryos and not allow them to implant. If that went well, there would be no pregnancy and the embryo would follow the ‘normal’ path of the menstrual cycle.

Environmental factors       

The following ‘external’ factors can be related to (recurrent) miscarriage:
  • smoking
  • alcohol 
  • heavy intake of caffeine
  • overweight
  • exposure to anaesthetic gases, tetrachloroethylene (used in dry cleaners), isotretinoine (medication for acne) and other toxic substances.
No connection with other external factors can be shown. There are no studies illustrating the effects of bedrest, physical exertion, physical activity or e.g. fitness programmes.

Hormonal factors       

Mild hormonal abnormalities have not been shown to lead to recurrent miscarriage. However, badly treated hormonal problems such as the following do increase the risk:
  • (unregulated) diabetes;
  • serious thyroid problems
  • polycystic ovarian syndrome.
  • prolactine level in the blood that is too high; and
  • low progesterone levels in the period following the implantation of the embryo.

Anatomical abnormalities         

In the general population, two to four per cent of women are found to have an abnormality in the uterus: fibroids inside and outside the uterus, the presence of a division (septum) or adhesions (Asherman syndrome). This defect is present from birth, and means the embryo is unable to develop properly.
In 10-15% of women who have had recurrent miscarriage, an abnormality in the uterus is found, often a septum.

Viral infections and immunological causes        

There is little hard evidence that infections can cause recurrent miscarriages. On the other hand, abnormalities in the immune system, although rare, can lead to recurrent miscarriage (see also scientific project).
In most cases, this is due to an excess in antibodies, against the body's own tissues and cells. This is known as an auto-immune condition. Recurrent miscarriage is often caused by the antiphospholipid syndrome.