Recurrent Miscarriage and Pregnancy Loss: Causes, Support and Options for Future Pregnancy
Pregnancy loss can be deeply distressing, whether it happens following natural conception or fertility treatment. It is also more common than many people realise. Around one in five women experience a miscarriage in the first three months following a positive pregnancy test.
For most people, miscarriage is not caused by anything they did or did not do. Understanding why pregnancy loss can happen, when further investigation may be helpful and what options are available for a future pregnancy can make the next steps feel a little clearer.
For some people undergoing IVF, this may also include a discussion about treatments such as preimplantation genetic testing for aneuploidy, or PGT-A. As with any fertility treatment, it is important to understand both its potential role and its limitations.
What do we mean by miscarriage and pregnancy loss?
In the UK, miscarriage is the loss of a pregnancy before 24 weeks. Most miscarriages happen during the first trimester.
Pregnancy loss is a broader term. It can also include ectopic pregnancy, where a pregnancy implants outside the uterus, and molar pregnancy, where abnormal tissue develops following fertilisation. These are different conditions from miscarriage and require their own medical assessment and follow-up.
The Royal College of Obstetricians and Gynaecologists (RCOG) defines recurrent miscarriage as three or more first-trimester miscarriages1,2. Whilst European Society of Human Reproduction and Embryology (ESHRE) and American Society of Reproductive Medicine (ASRM) defines recurrent miscarriage as the loss of two or more pregnancies3,4. These do not need to happen consecutively, and healthy pregnancies may occur between losses. In some circumstances, a specialist may recommend investigation after two first-trimester miscarriages, particularly where the clinical history suggests there may be an underlying cause.
Why do miscarriages happen?
Chromosomal abnormalities in the developing pregnancy are the most common cause of miscarriage. It is estimated that around half of miscarriages happen because the pregnancy has developed with an abnormal number of chromosomes.
An embryo would usually have 46 chromosomes. Occasionally, an error occurs as the egg or sperm forms, or during the earliest stages of embryo development, resulting in too many or too few chromosomes. This is known as aneuploidy.
The likelihood of aneuploidy increases with the age of the woman whose eggs are being used, which is one of the reasons miscarriages becomes more common as maternal age increases.
There are other recognised factors associated with recurrent miscarriage. These include antiphospholipid syndrome (APS), certain differences in the shape of the uterus, thyroid problems, poorly controlled diabetes and, in a small proportion of couples, a chromosomal rearrangement carried by one of the parents.
Smoking, drinking excessive amounts of alcohol or caffeine, and being significantly underweight or overweight may also increase the chance of miscarriage.
Having one of these risk factors does not mean that it caused an individual pregnancy loss. Even after thorough investigation, many cases of recurrent miscarriage remain unexplained.
Most importantly, miscarriage is very rarely the result of something you deliberately did or failed to do.
The emotional impact of pregnancy loss
Pregnancy loss is not simply a clinical event.
For many individuals and couples, it can bring grief, anxiety, guilt and uncertainty about trying for another pregnancy. After recurrent miscarriage, it is also understandable to lose confidence that a future pregnancy will progress normally.
There is no single way to experience pregnancy loss and no set timeframe for recovery. Some people want to talk about what has happened straight away, while others need more time.
Support may come from your fertility specialist, GP, counsellor, family and friends, or from organisations specialising in pregnancy loss such as Miscarriage UK, Tommy’s and Sands
A good fertility consultation should make room for this emotional experience as well as addressing the medical questions.
When should you seek medical advice?
Bleeding or pain during early pregnancy does not always mean that a miscarriage is happening, but it should be assessed5.
If you experience vaginal bleeding, persistent abdominal pain, feel unwell or have symptoms that concern you, contact your Early Pregnancy Assessment Unit, GP or NHS 111.
Heavy bleeding, severe abdominal pain, shoulder-tip pain, marked dizziness, fainting or loss of consciousness requires immediate medical attention. These symptoms can occur with significant bleeding or an ectopic pregnancy. Call 999 or attend A&E if you have severe symptoms.
If you have experienced repeated miscarriages, a consultation with a specialist in recurrent miscarriage can help determine whether further investigation is appropriate.
How is recurrent miscarriage investigated?
The starting point is a detailed discussion about your individual history. This includes previous pregnancies and losses, fertility treatment, medical conditions, age and any relevant family history.
Depending on your circumstances, investigations may include but not limited to blood tests for antiphospholipid syndrome and thyroid function, testing for diabetes where clinically indicated, and a pelvic ultrasound to look at the uterus.
Genetic testing may also be appropriate in some cases. Following a third or subsequent miscarriage, testing pregnancy tissue may be recommended to look for chromosomal abnormalities. Chromosome testing for both partners may also be considered where the results suggest a possible inherited problem, or where pregnancy tissue cannot be tested.
If there is a reason to look more closely at the uterine cavity or the shape of the uterus, further imaging may be recommended. This can include three-dimensional ultrasound and, depending on the findings, other investigations such as saline infusion sonography or hysteroscopy.
The purpose of recurrent miscarriage assessment is not to perform every available test. Investigations should have a clear clinical reason behind them, and your consultant should explain what the results may mean and whether they would change your treatment.
Can PGT-A reduce the risk of miscarriage?
For some patients undergoing IVF, preimplantation genetic testing for aneuploidy (PGT-A) may be part of the discussion.
PGT-A is an embryo-selection technique used to assess the number of chromosomes in embryos created through IVF. Embryos are usually grown to the blastocyst stage, around day five or six, before a small number of cells are removed from the part of the embryo that will go on to form the placenta. These cells are then analysed in a specialist genetic laboratory.
The results can help identify embryos reported as having the expected number of chromosomes, known as euploid embryos, so that these can be prioritised for transfer.
The HFEA currently considers there to be good evidence that PGT-A can reduce the chance of miscarriage for fertility patients overall6. However, this does not mean that it prevents all miscarriages, nor does it guarantee a successful pregnancy. Chromosomal abnormalities are only one possible cause of pregnancy loss.
It is also important to distinguish between reducing the chance of miscarriage after embryo transfer and increasing the overall chance of having a baby. The HFEA currently rates PGT-A red for improving the chance of a baby for most fertility patients because it is a selection technique and can reduce the number of embryos available for transfer.
For older women, there is a clear biological reason why PGT-A may be considered, because a greater proportion of embryos are likely to be aneuploid as age increases. However, the HFEA currently considers the evidence specifically in older women insufficient to reach a firm conclusion about whether PGT-A reduces miscarriage or improves the chance of having a baby.
This is why PGT-A should be considered in the context of your age, ovarian reserve, number of embryos available, previous treatment and wider fertility history, rather than recommended on age alone.
Could PGT-A make treatment more efficient?
For some patients with several embryos available, PGT-A may help decide which embryo to transfer first and reduce the likelihood of transferring an embryo found to be aneuploid.
For an individual patient, this could mean avoiding some unsuccessful embryo transfers or miscarriages. It should not, however, be presented as a guaranteed way to shorten the fertility journey.
PGT-A is therefore best understood as a tool for selecting embryos, rather than a treatment that guarantees pregnancy or increases the total number of embryos available.
Treatment, support and planning your next pregnancy
If recurrent miscarriage investigations identify a specific cause, treatment can be tailored accordingly.
For example, women with antiphospholipid syndrome and recurrent miscarriage may be offered low-dose aspirin and heparin during pregnancy. Thyroid disease and diabetes should be appropriately controlled.
Some abnormalities affecting the uterus may warrant further assessment or treatment, although whether surgery improves pregnancy outcomes depends on the type of abnormality and your individual circumstances.
Progesterone has an evidence-based role in a specific group of women. NICE recommends vaginal micronised progesterone for women who have bleeding in early pregnancy, have previously experienced a miscarriage and have an intrauterine pregnancy confirmed on ultrasound7. It is not recommended as a universal treatment for unexplained recurrent miscarriage.
If you are undergoing IVF and embryo aneuploidy may be relevant, your fertility specialist can also discuss whether PGT-A is appropriate for you and explain the possible advantages, limitations and alternatives.
Support during a future pregnancy can be equally important, particularly after recurrent miscarriage. This may include early clinical review, reassurance scans where appropriate, clear advice about symptoms and access to a clinical team familiar with your history. RCOG specifically recognises the importance of supportive care for women experiencing recurrent miscarriage.
Recurrent miscarriage care at Consilium Clinic
At Consilium Clinic in London, recurrent miscarriage and fertility care is consultant-led and individualised.
Rather than looking at a single test result or treatment in isolation, we consider your pregnancy history, age, ovarian reserve, previous fertility treatment, and personal priorities together.
If you have experienced miscarriage or recurrent pregnancy loss and would like to understand what it may mean for a future pregnancy, a specialist consultation can help you review your history, consider whether further investigation is appropriate and discuss your options clearly.
Sources
Royal College of Obstetricians and Gynaecologists (RCOG). Early miscarriage. RCOG: Early miscarriage
Royal College of Obstetricians and Gynaecologists (RCOG). Recurrent miscarriage. RCOG: Recurrent miscarriage
European Society of Human Reproduction and Embryology (ESHRE). Recurrent Pregnancy Loss. ESHRE: Recurring Pregnancy Loss
American Society for Reproductive Medicine (ASRM). Recurrent Pregnancy Loss:
A Committee Opinion. ASRM: Recuring Pregnancy Loss
NHS. Miscarriage. NHS: Miscarriage
Human Fertilisation and Embryology Authority (HFEA). Pre-implantation genetic testing for aneuploidy (PGT-A). HFEA: PGT-A
National Institute for Health and Care Excellence (NICE). Ectopic pregnancy and miscarriage: diagnosis and initial management (NG126). NICE guideline NG126
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