Defined in the UK as three or more consecutive miscarriages. In the USA the definition is two or more consecutive miscarriages.
A patient who has had three or more miscarriages in a row is considered to have had recurrent miscarriages. According to the Royal College of Obstetricians and Gynaecologists, the issue affects around 1% of couples trying to conceive. It is also estimated that 1-2% of second-trimester miscarriages will happen before 24 weeks of gestation.
If a person has experienced recurrent miscarriages, their doctor or a specialist will often recommend further tests to check for underlying causes. For many, pregnancy loss will be the result of chromosomal or genetic abnormalities. These abnormalities may come from the egg, the sperm cell, both, or even from the early embryo itself. However, causes may not always be apparent and on occasion, a pregnancy may end at random. For around 50% of cases, no underlying cause will present itself in a way that pinpoints it as the reason behind the miscarriage.
There are three tests that your doctor or healthcare professional may recommend to determine a cause if you have experienced recurrent miscarriages. These are offered after consultation, in which they will take a detailed medical, surgical, family, and genetic history. They may also perform a physical examination before the tests are recommended.
We have provided more detail on each of the tests below:
A patient’s blood may be checked for high levels of the antiphospholipid (aPL) antibody and lupus anticoagulant. Both of these are antibodies related to the antiphospholipid syndrome, which experts have linked to pregnancy loss.
The antibodies are also known to increase the chance of blood clots, as well as change the way that placenta attaches. These blood clots and the changes associated with the placenta can reduce the blood supply to the foetus, which may result in a miscarriage.
Blood tests to check for causes of recurrent miscarriages should be conducted twice, a few weeks apart, while the patient is not pregnant.
After a third miscarriage, a specialist will normally recommend that the foetus is tested for abnormalities in its chromosomes. If a genetic abnormality is found, the patient and their partner may also then be tested for abnormalities in their chromosomes, as this may be the root of the issue. This will involve profiling their chromosomes to look at their appearance and number, in a test known as karyotyping.
Genetic tests will normally be carried out using a sample of blood or saliva. The sample will then be sent to a genetic testing laboratory to be analysed.
If karyotyping detects problems with the patient or their partner’s chromosomes, they may be referred to a clinical geneticist. As experts in genes, these professionals will be able to explain a couple’s chances of achieving a successful pregnancy in the future. They are also likely to suggest fertility treatments, such as in-vitro fertilisation (IVF), that the couple may be able to try and succeed with. This advice is known as genetic counselling.
Having a transvaginal ultrasound scan carried out may determine whether or not the patient’s womb has any abnormalities. A second procedure may then be arranged, using a 3D ultrasound scanner to study the patient’s lower abdomen and pelvis. Doing this often provides a more accurate diagnosis.
These ultrasound scans can also help check if the patient has a weakened cervix.
The test can only usually be carried out if the patient becomes pregnant again. As such, a doctor will normally ask their patient to come for a scan when they are between 10 and 12 weeks pregnant.