Recurrent Miscarriage: Causes
Recurrent miscarriage is defined as three or more consecutive pregnancy losses, and it's understandably one of the most distressing experiences a woman can go through. It's rare, but it's also one of the situations where NHS guidelines specifically recommend investigation, because in a meaningful proportion of cases a treatable or manageable cause can be found. Here's an overview of what's typically looked into.
Chromosomal and genetic factors
The most common identifiable cause of any single miscarriage, including recurrent ones, is a chromosomal abnormality in the developing pregnancy — essentially a one-off genetic error that isn't compatible with ongoing development. This becomes more likely with maternal age. Less commonly, one partner may carry a balanced chromosomal rearrangement that doesn't affect their own health but can increase the chance of miscarriage. This is checked for with blood tests from both partners if recurrent loss has occurred.
Blood clotting and immune factors
- Antiphospholipid syndrome (APS) is an autoimmune condition affecting blood clotting that is strongly linked to recurrent miscarriage. It's diagnosed with blood tests and, if confirmed, is often treatable with medication such as low-dose aspirin and/or heparin injections during pregnancy.
- Inherited thrombophilias (clotting tendencies that run in families) are sometimes tested for, though their link to recurrent miscarriage is less clear-cut than APS.
Structural and hormonal causes
- Uterine abnormalities, such as a womb septum (a band of tissue dividing the uterine cavity) or large fibroids, can sometimes interfere with implantation or the space available for the pregnancy to grow. These may be picked up on scans or specialist imaging.
- Cervical weakness (sometimes called cervical incompetence) is more commonly linked to later pregnancy loss rather than early recurrent miscarriage, but is considered as part of a fuller assessment.
- Thyroid problems and PCOS can affect hormone balance in ways that make it harder to sustain an early pregnancy, so thyroid function and related hormone levels are commonly checked.
When no cause is found
It's important to know that in a substantial number of cases, thorough testing finds no clear cause. This can feel unsatisfying, but it isn't the same as there being nothing that can be done — many women in this situation go on to have successful pregnancies with simply closer monitoring and support in future pregnancies, without needing a specific treatment.
Frequently Asked Questions
How common is recurrent miscarriage?
Recurrent miscarriage, defined as three or more consecutive losses, is uncommon, affecting a small proportion of couples trying to conceive. It's distressing, but it's also actively investigated by the NHS, and many affected couples go on to have successful pregnancies, whether or not a specific cause is identified.
What tests are done for recurrent miscarriage?
Testing after three consecutive losses typically includes blood tests for antiphospholipid syndrome and thyroid function, chromosome analysis for both partners, and pelvic ultrasound or other imaging to check the shape of the womb. Your GP will usually refer you to a specialist recurrent miscarriage clinic for this assessment.
Can recurrent miscarriage be prevented or treated?
It depends on the cause. When a specific issue like antiphospholipid syndrome or a structural problem is found, targeted treatment can significantly improve the chances of a successful pregnancy. Where no cause is found, closer monitoring and early support in subsequent pregnancies is usually the recommended approach.
This article is for informational purposes only and does not constitute medical advice.
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