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Recurrent Miscarriage
- How common is recurrent miscarriage?
- What can cause recurrent miscarriage?
- What does not cause recurrent miscarriage?
- What investigations can be done?
- What treatments are available?
- Why did it happen - was it my fault?
- How long will the bleeding last and when will my periods return?
- I had a D&C - will this cause any problems?
How Common is Recurrent Miscarriage?
Pregnancy loss or recurrent miscarriage (RM) is diagnosed when a woman miscarries 2 to 3 times consecutively, before 20 weeks gestation. It is true that some women miscarry more often than chance alone would expect. When considering how common recurrent miscarriage actually is, we need to consider some numbers.
It is well known that overall 15% of all clinically recognized pregnancies end in miscarriage. The main cause is a problem with the gene cross-over at time of conception. This is due to chance alone, and nothing can be done to prevent it. The miscarriage is nature's way of ensuring health throughout the whole of your offspring's life. When pregnancy is diagnosed much earlier, with very sensitive hormone tests, it is found in fact that up to 60% of pregnancies end in miscarriage - most would just present as a heavier late period if undiagnosed. So two early miscarriages may likely to be no more than just bad luck.
The risk of miscarriage decreases as pregnancy progresses. It is possible that as many as 50% of pregnancies miscarry before implantation in the womb occurs. Early after implantation, pregnancy loss rate is about 30% (i.e., this is still before a pregnancy is clinically recognized). After a pregnancy may be clinically recognized (between days 35-50), about 25% will end in miscarriage. The risk of miscarriage decreases dramatically after the 8th week as the weeks go by.
Many women miscarry more than once in their life. Considering the frequency of miscarriage, about 1 in 36 women will have 2 miscarriages due to nothing more than chance. Any miscarriages after that might prompt your doctors to suggest some tests to ensure that it isn't happening for some other reason. If you're worried have a chat with your family physician or gynecologist.
What is important to remember through all of this, is that 60% of women who have recurrent miscarriage (RM) will go on to have a successful pregnancy the next time - without any kind of tests or treatment. When a woman is investigated for RM, it is possible that no cause can be found.
Miscarriage may be more common after a previous miscarriage, or less common following previously normal pregnancies.
| First pregnancy | 5% |
| Last pregnancy terminated | 6% |
| Last pregnancy a live birth | 5% |
| All pregnancies live births | 4% |
| 1 previous miscarriage | 20% |
| 2 previous miscarriages | 28% |
| 3 previous miscarriages | 43% |
What Are the Causes of Recurrent Miscarriage?
Remembering that most often no cause is found, below are some of the things which are thought to be associated with RM:
- Chromosome problems (of the FETUS) – Occurs when the fetus has too many or too few chromosomes. (Such as Down’s Syndrome, or Turner’s Syndrome). Mom & Dad are genetically fine, but when put together an unusual gene mismatch occurs. This usually does not re-occur. These pregnancy losses can occur very early or sometimes late in the first trimester.
- Chromosome problems (of the Mom or Dad) - Although very rare, the mom or dad may have a minor chromosome problem, that only is important in reproduction. Testing of parental chromosomes is recommended if all other tests are normal. Unfortunately, if there is an abnormality, nothing can be done to change it; fortunately, it is unlikely to cause a miscarriage with each pregnancy, so it may just take several attempts before a healthy fetus results.
- Antiphospholipid antibody syndrome - this is an immune disease where the main problems are RM, clots in the veins or arteries and often a low count of one of the blood components, the platelets. If pregnancy is successful, it can be complicated by poor growth of the baby and a disease of pregnancy called preeclampsia (high blood pressure and excess protein in the urine).
- Uterine (womb) abnormality – Examples include a double-womb or a septum (wall) down the middle. Many times removal of a septum is all that is needed to improve the outcome of the next pregnancy. This is tested with either a special ultrasound (sonohysterogram) or an HSG (Hysterosalpingogram).
- Fibroids – benign tumors of normal uterus tissue growing in the muscle, sometimes causing misshaping of the womb cavity. This can interfere with implantation of the embryo or limit the amount of room the baby has to grow.
- Cervical incompetence (weakness) - may cause miscarriage in 2nd trimester. Some women are just born with a weak cervix. This is not as common as some people report, and the diagnosis is very difficult to make.
- Polycystic ovary syndrome (PCOS) - often this disease causes infertility or trouble even getting pregnant. It has also been found when this is present with a raised hormone level (LH) there is an increased risk of miscarriage. These patients may have an elevated insulin level which can affect the hormone environment important for the developing fetus. It is often treated with medications that improve ovulation or lower insulin.
- Immune problems - couples with RM may have some similar components of the immune system. This can make it difficult for mom to make the appropriate response to pregnancy. This is a controversial finding, but can be checked if everything else is normal.
- Hormone 'deficiency' - in pregnancies which end in miscarriage, sometimes the levels of a hormone called progesterone are found to be low. This is thought to reflect an early pregnancy failure, and is probably the RESULT rather than the cause of the miscarriage. Although progesterone has never been proven to be helpful in preventing pregnancy loss, it is frequently given as it may help a small subset of patients and doesn’t hurt, except to make the patient feel more fatigued.
Events Unlikely to Cause Recurrent Miscarriage
- Retroversion - or backward tilting of the uterus.
- Infection - such as toxoplasmosis, listeria, rubella, chlamydia, herpes simplex and cytomegalovirus.
- Endocrine or metabolic disease - hypothyroidism (under active thyroid), diabetes mellitus, Crohn's disease, sickle cell or endometriosis.
- Occupational exposures - very little reliable evidence exists for things such as herbicide spraying, electromagnetic fields, chemical inhalation, anaesthetic gases or VDU usage.
- Not resting enough - bed rest doesn't alter whether you miscarry or not. Nor does working when you're pregnant, exercise, making love or flying.
What Investigations Can be Done?
- Blood tests to test for hormone problems or PCOS
- Ultrasound of uterus
- Hysteroscopy or HSG (dye test) to look at the uterine cavity (womb)
- Chromosome testing of the husband and wife to test for genetic abnormalities
- Other specific testing for immune problems
Is There Any Treatment?
If any of the above tests should come back indicating an underlying reason for the problem, then treatment is directed at the cause - e.g. genetic counseling, removal of fibroids, cervical stitch. If all of the above have been excluded (as they will do in many cases), the diagnosis is recurrent miscarriage of unknown cause. The only intervention to have demonstrated benefit is serial ultrasound scans in the early months of pregnancy. It is certainly not unreasonable to expect this psychological support to improve outcome given the close interaction between the higher areas of the mind and the delicately balanced hormonal system.
Most patients who have no known causes are encouraged to take a baby aspirin (80 mg) to improve uterine artery blood flow and also help treat a possible undiagnosed immune problem. Some patients are given heparin (blood thinner) to treat immune problems (such as antiphospholipid antibody syndrome). Progesterone supplements have been evaluated in clinical trials and have not been shown to be of any benefit to most people. Some patients will truly benefit, but it’s hard to determine which patients will improve. Therefore, sometimes progesterone is prescribed with the hope of success (realizing it may not be any better then placebo).
Why Did It Happen - Was It My Fault?
When you conceive and a baby is created, it takes half its genes from the sperm and half from the egg that ovulated that month. At the exact time of conception, the cross-over of these genes takes place. Sometimes, for no reason other than bad luck, some information is lost and the pregnancy is destined from that point not to be. It might be that this lost information is not needed for many weeks, and the pregnancy will continue as normal until that time. When the needed information is not there, it is then that the baby dies and you begin to miscarry. Sometimes when this happens, the miscarriage doesn't happen right away. This is called a 'missed' miscarriage and may not be picked up until some weeks later, following a slight loss or period-type pains. Another cause might be that the embryo did not implant, or bury itself, into the womb lining properly - once again, just due to bad luck.
These are the most common reasons that women miscarry. Not because of something you did or didn't do, but just because of chance. Not because you drank alcohol, ate some unpasteurized cheese, or didn't take folic acid. Certainly not because you had sex or didn't rest enough. Whether you lay in bed from the day of your positive pregnancy test or went hang-gliding every day wouldn't have changed things. Its nature's way of making sure that when you do have a baby, it has the best chance for all of its life. Miscarriage does not mean that you won't be able to get pregnant again.
How Long Will the Bleeding Last and When Will My Periods Return?
The loss will probably continue for about 7-10 days, tailing off toward the end of this time. It shouldn't be heavier than a period, and shouldn't have an offensive odor. If you're worried, see your General Practitioner or practice nurse for some advice. Normally your next period will come by 6 weeks or so. If they were irregular before, then it may be longer. Also, your fertility returns before your next period, so if you feel pregnant again a pregnancy test might be useful.
I Had a D&C - Will This Cause Any Problems?
A D&C (dilatation and curettage) or evacuation is carried out to reduce the chance of infection and ensure that you don't continue bleeding over the following weeks. Very rarely, it can cause infection of the womb lining with persistent loss or an offensive odor. We believe that the chance of this is less likely than had you not undergone a D&C. If this happens it usually responds well to a short course of antibiotics. The D&C doesn't weaken your cervix or make you more likely to miscarry in subsequent pregnancies.