There is a particular kind of grief that comes with recurrent miscarriage that doesn’t get talked about enough. Each loss arrives with its own weight, and by the second or third, the grief has layers to it. There’s the loss itself, and then there’s the fear about what it means, the unanswered questions, and often a quiet feeling of being let down by your own body.
If you’ve had more than one miscarriage and you’re trying to understand what might be happening and what can be done, this piece is for you. It’s written to be clear and honest, not clinical and distant. Because this topic deserves both accuracy and gentleness.
When does it become “recurrent”
This is worth clarifying upfront because definitions vary and can cause confusion.
The American Society for Reproductive Medicine (ASRM) defines recurrent pregnancy loss as two or more failed clinical pregnancies. A clinical pregnancy means one that was confirmed on ultrasound or through pathological examination, not just a positive test. Some guidelines and clinics historically used three or more as the threshold, but the current ASRM position is two or more, and most specialists will begin a structured investigation at that point rather than waiting for a third loss.
One miscarriage, as painful as it is, is not uncommon. Studies suggest that anywhere from 10 to 20 percent of confirmed pregnancies end in miscarriage, and the true rate including very early losses is likely higher. A single miscarriage does not, on its own, indicate that something is systematically wrong. Two or more is when investigation starts to make clinical sense.
That said, there is no rule that says you have to wait. If you have had one loss and have other risk factors, or if you simply want to understand more about your situation before trying again, a conversation with a specialist is always appropriate.
Why this happens: the most common causes
The honest answer is that even after a thorough investigation, a cause is not always found. Around half of all recurrent miscarriage cases remain unexplained after a full workup. That is a difficult thing to sit with, but it’s important to say it plainly rather than imply that investigation always produces answers.
When a cause is identified, these are the most common ones.
Chromosomal abnormalities in the embryo
This is the most frequent explanation for individual miscarriages and plays a significant role in recurrent losses too. Embryos sometimes carry chromosomal errors that prevent normal development. This becomes more common with age, particularly for women over 35.
What most people don’t realise is that this is usually a random event, not an inherited one. The chromosomal error typically arises during the formation of the egg or sperm, or at fertilisation, and doesn’t necessarily reflect anything about either parent’s chromosomes.
In couples with recurrent pregnancy loss, testing the tissue from a miscarriage (called products of conception or POC testing) can sometimes identify whether a chromosomal abnormality was present in that particular pregnancy. This information, while it doesn’t prevent future losses on its own, can help guide investigation and treatment planning.
Parental chromosomal factors
In a smaller proportion of couples with recurrent pregnancy loss, roughly 2 to 5 percent, one partner carries a structural chromosomal rearrangement called a balanced translocation. The carrier is typically healthy and unaware of it. But when the chromosomes are passed to an embryo, the balance can be disrupted, resulting in a chromosomally abnormal pregnancy that miscarries.
This is identified through karyotype testing of both partners, which is a standard part of the recurrent miscarriage workup.
Antiphospholipid syndrome
This is one of the most clinically important causes to identify because it is treatable.
Antiphospholipid syndrome, or APS, is an autoimmune condition in which the body produces antibodies that increase the tendency for blood to clot. In pregnancy, this can impair blood flow through the placenta and is associated with recurrent miscarriage, particularly in the second trimester, as well as with other pregnancy complications.
APS is diagnosed through blood tests for specific antibodies: anticardiolipin antibodies, anti-beta-2 glycoprotein I antibodies, and lupus anticoagulant. Because these can be temporarily elevated after an infection or illness, a positive result needs to be confirmed on a repeat test at least 12 weeks later before a diagnosis is made.
When APS is confirmed, treatment with low-dose aspirin and low molecular weight heparin during pregnancy has good evidence behind it and significantly improves live birth rates in this group.
Uterine abnormalities
The structure of the uterus matters. Certain uterine abnormalities, either present from birth or developed over time, can interfere with implantation or the developing pregnancy.
A septate uterus, where a band of tissue divides the uterine cavity, is the most common congenital uterine abnormality associated with recurrent miscarriage and is surgically correctable through a hysteroscopic procedure.
Other structural issues include submucous fibroids (fibroids that protrude into the uterine cavity), uterine polyps, and intrauterine adhesions (scar tissue inside the cavity, sometimes following a previous procedure).
These are typically identified through ultrasound, a saline infusion sonogram, or hysteroscopy.
Hormonal and thyroid factors
Thyroid function is checked as part of most recurrent miscarriage investigations. Both underactive thyroid (hypothyroidism) and even TSH levels that fall within the laboratory reference range but are higher than ideal for conception and pregnancy have been associated with pregnancy loss. The current recommendation is that TSH levels should ideally be below 2.5 mIU/L in women who are pregnant or trying to conceive, though guidelines vary and your doctor’s interpretation of your specific levels matters.
Poorly controlled diabetes and elevated prolactin are also included in a standard hormonal workup.
Polycystic ovarian syndrome (PCOS) has been associated with higher miscarriage rates in some studies, though the precise mechanism and how best to address it in the context of recurrent loss is still an area of ongoing discussion in reproductive medicine.
Immune factors
This is the most contested area in recurrent miscarriage research, and it’s worth being clear about that.
There is genuine scientific interest in whether the immune environment of the uterus plays a role in some cases of recurrent pregnancy loss. Elevated uterine natural killer cell activity has been studied as a proposed mechanism. Various immune therapies have been tried, including steroids, intralipid infusions, and intravenous immunoglobulin.
However, most of these interventions do not yet have consistent, high-quality evidence behind them. They are not universally recommended in standard guidelines. Some clinics offer them more readily than the current evidence supports. If immune treatment is recommended to you, it’s entirely reasonable to ask what specific finding in your case suggests it, and what the evidence is for the proposed treatment.
The tests that make up a standard workup
A structured recurrent miscarriage investigation typically covers the following:
Karyotype testing for both partners, to check for balanced translocations or other chromosomal rearrangements.
Antiphospholipid antibody panel: anticardiolipin antibodies (IgG and IgM), anti-beta-2 glycoprotein I antibodies (IgG and IgM), and lupus anticoagulant. Repeated after 12 weeks if initially positive.
Pelvic ultrasound to assess the uterine cavity and ovarian reserve. A 3D ultrasound or saline infusion sonogram gives a clearer view of the uterine shape than a standard 2D scan.
Hysteroscopy in some cases, particularly if ultrasound suggests a possible uterine anomaly or intrauterine abnormality that needs direct visualisation.
Thyroid function tests including TSH, and sometimes T4 and thyroid antibodies.
Hormonal panel including prolactin, and sometimes fasting glucose and insulin depending on the clinical picture.
Products of conception testing, where possible, from a subsequent miscarriage. Getting chromosomal analysis of the pregnancy tissue, when available, adds valuable information to the picture.
Some specialists also offer extended thrombophilia screens beyond the antiphospholipid antibodies. The evidence for treating other thrombophilias in recurrent miscarriage is less established than for APS, and which tests are run may depend on the individual clinical history.
Two hypothetical situations that show how this plays out differently
Consider a hypothetical couple with three first-trimester miscarriages. The woman is 34. Full workup returns a positive anticardiolipin antibody result, confirmed on repeat testing 12 weeks later. A diagnosis of antiphospholipid syndrome is made. In a situation like this, the path forward is relatively clear. Treatment with low-dose aspirin and low molecular weight heparin in the next pregnancy has a meaningful evidence base. The investigation produced an answer, and the answer has a treatment. This is one of the more hopeful scenarios within recurrent miscarriage, precisely because the cause is identifiable and manageable.
Now consider a different hypothetical. A couple with two confirmed miscarriages, both in the first trimester. The woman is 38. Full workup: normal karyotype for both partners, negative antiphospholipid panel, normal uterine cavity on hysteroscopy, normal thyroid, normal hormones. Products of conception testing from the second miscarriage shows a chromosomal trisomy in that pregnancy. The investigation returns no structural, immunological, or inherited explanation. In a profile like this, age-related chromosomal factors in the eggs are likely contributing. The options to discuss include close monitoring and support in the next natural pregnancy, or moving to IVF with PGT-A to screen embryos for euploid status before transfer. Neither path eliminates all risk, but both are informed by the specific clinical picture.
These two hypotheticals show why the same diagnosis of recurrent miscarriage leads to very different conversations, depending entirely on what the investigation finds, or doesn’t.
When to see a specialist and what to ask
Two or more confirmed clinical miscarriages is the point at which a referral to a specialist in recurrent pregnancy loss is clinically appropriate. You do not need to wait for a third.
Some questions worth asking at that appointment:
What specific tests are you recommending and why? A thorough workup should cover at least the categories listed above, and the reasoning should be explained.
Will products of conception from any future pregnancy be tested? Getting chromosomal information from a miscarriage, where possible, is genuinely useful.
If investigation comes back normal, what are the treatment options? This is where the conversation about close monitoring, progesterone support, aspirin, or PGT-A may be relevant depending on the profile.
What is your experience with recurrent pregnancy loss specifically? This is a subspecialty. Not every general gynaecologist or fertility specialist has dedicated expertise in it.
What treatment looks like when a cause is found
APS: low-dose aspirin started before or early in pregnancy, combined with low molecular weight heparin from a positive pregnancy test. This has good evidence and significantly improves outcomes in confirmed APS.
Uterine septum or submucous fibroids: hysteroscopic surgery to remove the septum or fibroid, followed by a recovery period before attempting pregnancy again.
Thyroid dysfunction: medication to optimise TSH levels before and during pregnancy.
Parental balanced translocation: natural conception is still possible, and some pregnancies will be unaffected. PGT-SR (preimplantation genetic testing for structural rearrangements) through IVF can be used to identify embryos with balanced or normal chromosomal arrangements before transfer, for couples who choose to pursue that path.
Age-related chromosomal factors: PGT-A through IVF is an option for couples who want to screen embryos for euploid status before transfer, reducing the likelihood of transferring an embryo that will miscarry. This doesn’t address egg quality itself, but it increases the proportion of transfers that involve chromosomally normal embryos.
When the investigation finds nothing
This is the part that deserves the most honest conversation.
Around half of couples who go through a full recurrent miscarriage workup will not receive a clear explanation. That is genuinely hard. There’s a tendency to assume that if the tests are thorough enough, an answer will emerge. Sometimes it doesn’t.
The role of progesterone support in unexplained recurrent miscarriage remains an area of ongoing discussion. The PROMISE trial did not show a statistically significant overall improvement in live birth rates with progesterone in unexplained recurrent miscarriage. Later studies and subgroup analyses have suggested possible benefit in some women, particularly those with early pregnancy bleeding and prior losses, but this remains an evolving area and not a settled one. Your doctor’s recommendation will depend on your specific clinical picture.
Some studies have associated close monitoring and supportive care in subsequent pregnancies with improved outcomes for women with unexplained recurrent loss, and most specialist clinics offer early pregnancy surveillance as part of their management approach.
What the evidence does not support: routine use of aspirin, heparin, steroids, or immune therapies in unexplained recurrent miscarriage in the absence of specific findings that indicate these treatments. Prescribing them without a clear indication is not supported by current guidelines and carries its own risks.
The most honest framing for unexplained recurrent pregnancy loss is this: the prognosis is often better than it feels. Many couples with unexplained recurrent loss do go on to have a successful pregnancy, particularly with close monitoring and appropriate support. That is not a guarantee, and it doesn’t erase what has already been lost. But it is an accurate picture of what the evidence shows.
You deserve more than “just keep trying”
Recurrent miscarriage is one of the areas in reproductive medicine where patients are sometimes told to wait longer before investigation begins, or where investigation is done but results are returned without enough explanation. If you have had two or more losses, you are entitled to a structured workup and a specific conversation about your results.
You are also entitled to take time. Between losses, between appointments, between decisions. The clinical pathway matters, but so does the space to process what has happened before moving to what’s next.
At 9M Fertility, recurrent pregnancy loss is approached as a distinct clinical area, not a subset of general infertility management. If you’ve had two or more miscarriages and want to understand what investigation is appropriate for your situation, that conversation is one we take seriously.
Book a consultation at 9M Fertility.
→ Also read: Chemical Pregnancy: What It Is, Why It Happens and What It Means for Future IVF
→ Also read: PGT-A Testing: How Genetic Screening Can Improve Your IVF Success Rate
