What is recurrent miscarriage?

A miscarriage is when you lose a pregnancy at some point in the first 28 weeks. When this happens three or more times doctors call this recurrent miscarriage. Around one woman in every 100 has recurrent miscarriages. This is about three times more than you would expect to happen just by chance, so it seems that for some women there must be a specific reason for their losses. For others, however, no underlying problem can be identified; their repeated miscarriages may be due to chance alone.

Often, in spite of careful investigations, the reasons for recurrent miscarriages cannot be found. However, if you and your partner feel able to keep trying, you still have a good chance of a successful birth in future. There are a number of things which may play a part in recurrent miscarriage.

	Your age and past pregnancies
	The older you are, the greater your risk of having a miscarriage. The more miscarriages you have had already, the more likely you will be to have another one.
	Genetic factors
	For around three to five in every 100 women who have recurrent miscarriages, they or their partner have an abnormality on one of their chromosomes. Although such abnormalities may cause no problem for you or your partner, they may sometimes cause problems if passed on to your baby.
	Abnormalities in the embryo
	An embryo is a fertilised egg. An abnormality in the embryo is the most common reason for single miscarriages. However, the more miscarriages you have, the less likely this is to be the cause of them.
	Autoimmune factors
	Antibodies are substances produced in our blood in order to fight off infections. Some people produce antibodies that react against the body’s own tissues; this is known as an autoimmune response and it is what happens to women who have antiphospholipid antibodies (aPL) antibodies. If you have aPL antibodies and a history of recurrent miscarriage, your chances of a successful pregnancy may be only one in ten.
	Sucture of the uterus
	Women who have serious anatomical abnormalities and do not have treatment for them seem to be more likely to miscarry or give birth early. Minor variations in the structure of your womb do not cause miscarriages
	Weak cervix
	In some women the entrance of the uterus (cervix) opens too early in the pregnancy and causes a miscarriage in the third to sixth month. This is known as having a weak (or ‘incompetent’) cervix.
	Polycystic ovaries
	If you have polycystic ovaries your ovaries are slightly larger than normal ovaries and produce more small follicles than normal. This may be linked to an imbalance of hormones. Many women with polycystic ovaries have recurrent miscarriages
	Infections
	If a serious infection gets into your bloodstream it may lead to a miscarriage. If you get a vaginal infection called bacterial vaginosis early in your pregnancy, it may increase the risk of having amiscarriage around the fourth to sixth month or of giving birth early. It is not clear, though, whether infections cause recurrent miscarriage; for this to happen, the bacteria or virus would need to be able to survive in your system without causing enough symptoms to be noticed. This rules out illnesses like measles, herpes, listeria, toxoplasmosis and cytomegalovirus (so you do not need to be tested for them if you have recurrent miscarriages).
	Diabetes and thyroid problems
	Diabetes or thyroid disorders can be factors in single miscarriages. They do not cause recurrent miscarriage, as long as they are treated and kept under control.

What can be done?

Supportive antenatal care

Women who have supportive care from the beginning of a pregnancy have a better chance of a successful birth.

Screening for abnormalities in the structure of your uterus

You should be offered a pelvic ultrasound scan to check for and assess any abnormalities in the structure of your uterus, so that they can be treated if necessary. Another method of screening is by using hysterosalpingography (an X-ray of the fallopian tubes using fluid injected through the entrance of the uterus).

Screening for genetic problems

You and your partner may be offered a blood test to check for chromosome abnormalities; the test is known as karyotyping. Your doctor will tell you what your chances are for future pregnancies and will explain what your choices are.

Screening for abnormalities in the embryo

If you have a history of recurrent miscarriage and you lose your next baby, your doctors may suggest checking for abnormalities in the embryo or the placenta afterwards. They will do this by checking the chromosomes of the embryo through karyotyping, although it is not always possible to get a result. They may also examine the placenta through a microscope. The results of these tests may help them to identify and discuss with you your possible choices and treatment.

Screening for vaginal infection

If you have had miscarriages in the fourth to sixth month of pregnancy or if you have a history of going into labour prematurely, you may be offered tests (and treatment if necessary) for an infection known as bacterial vaginosis (BV). If you have BV, treatment with antibiotics may help to reduce the risks of losing your baby or of premature birth.

There is evidence that if you have aPL antibodies and a history of recurrent miscarriages, treatment with low-dose aspirin tablets and low-dose heparin injections in the early part of your pregnancy may improve your chances of a live birth. Even with treatment, you will have a risk of extra problems during pregnancy (including high blood pressure, restriction in the baby’s growth and premature birth). You should be carefully monitored so that you can be offered appropriate treatment for any problems that arise.

Tests and treatment for a weak cervix

If you have a weak cervix, a vaginal ultrasound scan during your pregnancy may indicate whether you are likely to miscarry. If you have a weak cervix you may be offered an operation to put a stitch in your cervix, to make sure it stays closed. Because all operations involve some risk, your doctors should only suggest it if you and your baby are likely to benefit.

Hormone treatment

It has been suggested that taking progesterone or human chorionic gonadotrophin hormones early in pregnancy could help prevent a miscarriage.

What could it mean for me in future?

Your doctors will not be able to tell you for sure what will happen if you become pregnant again. However, even if they have not found a definite reason for your miscarriages, you still have a good chance (three out of four) of a healthy birth.

	You have the right to be fully informed about your health care and to share in making decisions about it. Your healthcare team should respect and take your wishes into account.
	No treatment can be guaranteed to work all the time for everyone.