You’re defined as having recurrent miscarriages if you’ve had three losses in a row. Sometimes, it can suggest there’s an underlying issue, so your doctor will suggest undergoing tests to find out if there’s a cause for your miscarriages.
Why you may be offered tests
Sadly, early miscarriage is really common. It usually happens because of a one-off chromosomal problem, and in most cases, doesn’t affect the next pregnancy. For that reason, you won’t automatically be offered a test after one miscarriage, or even two. It’s unlikely a cause will be found and it usually isn’t necessary to look for one. Most women go on to have a healthy pregnancy after a miscarriage. The exception may be if you had a miscarriage after 14 weeks, as this is more likely to have a cause that can be pinpointed. You can also choose to have tests privately if you’ve only had one or two miscarriages.
If you’ve had three miscarriages in a row, it’s more likely there may be an underlying reason that can be identified and treated, so your doctor should suggest tests to look into this. Sometimes, doctors may suggest investigations after two miscarriages, for example, if you’re in your late thirties or early forties, it’s taken a long time to conceive in the first place, or if you’ve had a lot of fertility treatment to help you conceive. You should be offered tests regardless of whether or not you already have children.
Possible causes and next steps
These are some of the most common known causes of recurrent miscarriage doctors are likely to test you for – and what can be done about them.
Antiphospholipid syndrome (APS)
Sometimes known as Hughes syndrome, it happens when your immune system makes substances called antibodies that attack a type of fat in your blood. It makes your blood thicker and more likely to clot – the reason the condition is also sometimes called ‘sticky bloody syndrome’. Although experts don’t know for sure why this is linked with miscarriage, the theory is that it might stop the pregnancy embedding properly in the uterus, or may interfere in some way with the way the placenta works.
The tests: You’ll be offered blood tests, usually given six to 12 weeks apart, to check for APS.
The treatment: You’ll be given blood-thinning medicines and monitored throughout your pregnancy. The good news is treatment has been shown to improve your chance of having a healthy pregnancy.
Other blood-clotting disorders
There’s a range of other blood-clotting problems, such as Factor V Leiden, which are inherited, and which you wouldn’t necessarily know you had. These can also interfere with development of a healthy pregnancy, and are more likely to cause a late miscarriage than an early miscarriage
The tests: Again, blood tests can pinpoint these.
The treatment: As with Hughes syndrome, blood-thinning medicines may help.
An incompetent cervix
A weakness in the cervix can mean it dilates far too early, causing miscarriage. It usually happens in the second trimester. Around one in 100 women are thought to have an incompetent cervix.
The tests: There isn’t actually a reliable test for this when you’re not pregnant. But if you conceive again, doctors will scan you regularly to monitor your cervix.
The treatment: You may be offered a cervical stitch around three months into a pregnancy. This is designed to strengthen the cervix. There’s no guarantee this will prevent further miscarriage but it is thought to help in some cases.
Occasionally, there may be a serious genetic issue inherited from one parent called a ‘unbalanced translocation’, where there’s too much of some genetic information, while other information is missing. It’s rare, but it’s something doctors may look into in recurrent miscarriage.
The tests: Tissue from a previous pregnancy will be tested, which is straightforward if you miscarried in hospital or had surgical management, but more difficult if you miscarried at home. If testing reveals an unbalanced translocation, you will both be offered tests to see if one of you has the chromosome problem that causes this, which is called a ‘balanced translocation’.
The treatment: Unfortunately, there’s no treatment for this and you should be offered counselling to consider future pregnancies.
Abnormally shaped uterus
There’s less evidence for this, but it’s thought an abnormally shaped uterus – for example, one that is divided down the middle, known as a ‘septate uterus’ – may sometimes play a role in recurrent miscarriage. It’s hard to be sure because doctors don’t know how many women with abnormally shaped uteruses have healthy pregnancies.
The tests: A pelvic ultrasound exam is the usual starting point. If the uterus doesn’t look normal, this may be followed by other tests that look more closely inside it, such as a laparoscopy.
The treatment: You may be offered surgery to correct the shape of the uterus, although there’s no evidence at the moment that this will reduce the risk of another miscarriage.
High levels of natural killer cells
You may read about a range of other causes, and treatments you can have. These include raised levels of natural killer (NK) cells in the uterus, which are thought to potentially attack a developing pregnancy. Private clinics often offer testing for NK cells, including steroid treatments to dampen their activity, and one small early study has shown this approach may help. But at the moment, we don’t have enough evidence to say this or other treatments are effective, and these are not available on the NHS. But speak to your doctor if you’d like to find out more.
When no cause is found
In around 50 per cent of cases of recurrent miscarriage, doctors aren’t able to find a cause. If this happens to you, it can be very distressing and frustrating. Often, it’s helpful to have answers. Even if treatment isn’t guaranteed to help, women can find it reassuring to know what’s gone wrong. Without that knowledge, you may feel very anxious about trying to conceive again. It can be difficult to balance hope for a healthy pregnancy with the uncertainty over why you’ve lost so many pregnancies in the past, and fear around it happening again.
That said, some women actually find it comforting to have known causes ruled out. After all, it shows there’s nothing specifically wrong, and you may feel reassured about that.
However you’re feeling, going through recurrent miscarriage and the rollercoaster of tests can be emotionally draining. So make sure you have support. You can seek counselling (speak to your doctor) or talk to a support organisation such as The Miscarriage Association.