Recurrent Pregnancy Loss

When a miscarriage happens three or more times in a row, it is called recurrent miscarriage.

What is the cause of recurrent miscarriage?

miscarriage

The simple answer is that quite often, nobody knows. In about half of cases, no cause is found after doing all the tests. In the other half, causes can be found and these include:

  • Abnormalities of the pregnant woman’s womb (uterus). For example, long-standing infection or inflammation of the womb (endometritis), scarring of the lining of the womb, lumps.
  • A weak (incompetent) neck of the womb (cervix), also known as cervical insufficiency. The cervix normally only opens at the time of labour to let the baby come out. In some women the cervix is lax and opens too early. This can be a cause of late miscarriages.
  • Antiphospholipid syndrome (APS). This is an abnormality of the immune system which results in blood being more likely than normal to clot (a thrombophilia). This can lead to unwanted blood clots (called thromboses) forming within blood vessels. This can affect the blood supply to the placenta and developing baby. You can read more about it in the separate leaflet called Antiphospholipid Syndrome. About 5 to 20 out of every 100 women with recurrent miscarriage have APS. This is an important cause, particularly as it can be treated.
  • Other abnormalities of the clotting system of the pregnant woman. Inherited conditions, such as factor V Leiden deficiency, can also make blood more likely to clot and it may be that this contributes to recurrent miscarriage, although this is not known for sure.
  • Abnormalities of the genes or chromosomes of the parents. Chromosomes are the structures that contain genes with the genetic information that we inherit from our parents. If a baby (fetus) has abnormal chromosomes it may not develop properly and so the pregnancy will end. Many miscarriages can be caused by abnormal chromosomes but it is usually a one-off abnormality which has occurred in the baby. Sometimes the parents have mild abnormalities of their chromosomes, which do not affect the parent, but which, when combined or divided to create a baby, can cause a major chromosome problem for the developing baby. If this is the case then recurrent miscarriages can happen.
  • Hormone problems. Lack of hormones needed for pregnancy may be involved in some cases. A condition called hyperprolactinaemia, and low thyroid hormone levels (hypothyroidism), can affect hormones needed to maintain pregnancy. Low progesterone levels in the early stages of pregnancy may affect the way the developing baby embeds (implants) in the womb.
  • Lifestyle factors. It may be that factors such as smoking, drinking excessive alcohol regularly or being very overweight contribute to the likelihood of having miscarriages.


What is the treatment for recurrent miscarriage?

This will depend whether a specific cause has been found after the tests described above. Possible treatments which may be advised include:

  • Both parents will normally be advised to have a think about any lifestyle factors which might be having an impact. The evidence is a little unclear about how important smoking, weight and alcohol intake are in contributing to recurrent miscarriage. However, it makes sense to address all these anyway as if any of them are an issue it may be relevant, and it will improve your general health.
  • If you have been found to have APS or certain other blood clotting problems then you will be advised to take blood-thinning medicines during future pregnancies.
  • Even if no cause has been found, blood-thinning medicines be taken in pregnancy but current evidence suggests this is not effective.
  • If a treatable abnormality of the womb has been found, an operation to correct it may reduce the risk of further miscarriage. For women with a weak neck of the womb (cervix), a stitch can be inserted in early pregnancy to keep it closed. This may help to prevent a miscarriage.
  • If either you or your partner are found to have abnormalities in your chromosomes, you would normally be referred to a specialist in genetics to advise you further. Some such couples may be given the option of pre-implantation genetic diagnosis. This essentially involves having in vitro fertilisation (IVF)
  • Some specialists have advised treating with a supplement of the hormone progesterone in early pregnancy, although the evidence is not clear about how beneficial this is. Further studies are ongoing to try to find out for sure.
  • Psychological support of some type may be helpful, as recurrent miscarriages are very distressing and are bound to affect you. It can put great strain on you both and your relationship. Some form of therapy may be helpful, such as counselling.

In many cases no cause is found and no treatment has really convincingly been found to be effective in this scenario. So no treatment may be appropriate for many couples. It is still good news when no cause is found, however, as this makes it more likely that future pregnancies will be successful.