Two miscarriages. That’s not a streak of bad luck – that’s a pattern, and your body is asking to be heard. If you’ve been told to “just try again” or that miscarriage is “very common,” you’re not wrong to want more than that. The science has caught up: current guidelines from the American Society for Reproductive Medicine (ASRM) and the European Society of Human Reproduction and Embryology (ESHRE) both recommend a full evaluation after two pregnancy losses, not three. You don’t have to wait for a third loss to start getting answers.
Why Two Losses Is Enough to Start Investigating
For years, the medical threshold was three consecutive miscarriages before a workup was triggered. That standard has shifted.
The ASRM’s 2026 Committee Opinion – the first major update in over a decade – now defines recurrent pregnancy loss (RPL) as two or more losses and explicitly supports beginning evaluation after the second. ESHRE’s 2023 guidelines align with this, particularly for women with non-consecutive losses or those over 35.
The reason this matters: roughly 50–80% of women with two prior miscarriages will go on to have a successful pregnancy, with or without treatment. But identifying a treatable cause – and there are several – can dramatically improve those odds and spare you from another loss.
Waiting is no longer the standard of care. Investigating is.
The Most Common Causes of Recurrent Pregnancy Loss
Before getting into the tests, it helps to understand what they’re actually looking for. Most recurrent losses fall into a handful of categories.
Chromosomal issues are the most common cause of any individual miscarriage – around 50% of early losses involve an embryo with an abnormal number of chromosomes (aneuploidy). This is usually random, but in some couples, one partner carries a balanced chromosomal translocation that silently increases the risk of abnormal embryos.
Uterine anatomy problems are found in roughly 15–20% of women with RPL. A uterine septum (a wall of tissue dividing the uterine cavity) is the most common structural issue. Fibroids, polyps, and scar tissue (Asherman’s syndrome) can also interfere with implantation and early development.
Antiphospholipid syndrome (APS) is an autoimmune condition where the immune system produces antibodies that interfere with blood clotting in the placenta. It’s one of the few fully treatable causes of recurrent loss – and one of the most important to identify.
Thyroid dysfunction is another treatable culprit. Even subclinical hypothyroidism (a TSH above 2.5 mIU/L) has been associated with increased miscarriage risk.
Uncontrolled diabetes and elevated prolactin levels round out the hormonal causes that a good workup will screen for.
In about 50% of RPL cases, no single cause is found – but that doesn’t mean testing is pointless. Ruling out treatable conditions is itself valuable, and the emotional weight of having done everything possible matters too.
The Tests: What Gets Ordered and Why
A structured RPL workup isn’t a single blood draw. It’s a stepwise investigation, and the most current guidelines are clear about what’s worth testing and what isn’t.
Step 1: Chromosomal Analysis of the Pregnancy Tissue
If tissue from the miscarriage was collected, chromosomal microarray testing (also called 24-chromosome microarray or array CGH) is the single highest-yield first step. It tells you whether the loss was caused by a chromosomal abnormality in the embryo itself.
- If the result is aneuploid (abnormal chromosomes): the loss was likely a random event. Further testing may be limited unless multiple aneuploid losses occur.
- If the result is euploid (chromosomally normal): the embryo was healthy, which means the cause lies elsewhere – in the uterus, the immune system, or the hormonal environment. This is the signal to investigate further.
This single test shapes everything that follows. It’s worth requesting it at the time of your miscarriage if at all possible.
Step 2: Uterine Cavity Imaging
For all women with unexplained RPL, ASRM recommends assessing the uterine cavity. The options include:
- Saline infusion sonohysterogram (SIS): An ultrasound with saline injected into the uterus to outline the cavity. Non-invasive and highly accurate.
- Hysterosalpingography (HSG): An X-ray with contrast dye, also used to check the fallopian tubes.
- Hysteroscopy: A small camera inserted into the uterus – the gold standard for both diagnosis and treatment.
If a uterine septum is found, hysteroscopic surgery to remove it has been shown to reduce miscarriage rates by approximately 55% and dramatically improve live birth rates. It’s one of the clearest win-conditions in RPL care.
Step 3: Antiphospholipid Syndrome (APS) Testing
This is one of the most important panels to run, especially if your losses were chromosomally normal. The diagnosis requires two positive tests at least 12 weeks apart for any of the following:
- Lupus anticoagulant
- Anticardiolipin antibodies (IgG or IgM)
- Anti-β2-glycoprotein I antibodies (IgG or IgM)
The reason the 12-week gap matters: a single positive result can be a transient finding. Two positives confirm a true autoimmune pattern.
If APS is confirmed, treatment with low-dose aspirin plus low-molecular-weight heparin during pregnancy achieves live birth rates of 71–90% – compared to roughly 10% without treatment. This is one of the most dramatic turnarounds in reproductive medicine.
Step 4: Thyroid and Hormonal Screening
A full thyroid panel – TSH and thyroid peroxidase (TPO) antibodies – is standard. The target TSH for women trying to conceive or in early pregnancy is below 2.5 mIU/L. Elevated TPO antibodies, even with a normal TSH, are associated with increased miscarriage risk and warrant monitoring.
Additional hormonal screening includes:
- Hemoglobin A1c (HbA1c): To screen for undiagnosed or poorly controlled diabetes
- Prolactin: Elevated levels can disrupt implantation and early pregnancy
Step 5: Parental Karyotyping
Both partners can have their chromosomes analyzed through a blood test. This checks for balanced translocations – rearrangements where chromosomal material has shifted but no genetic information is lost for the carrier, yet can cause significant abnormalities in embryos.
The yield from this test is relatively low (found in about 2–5% of RPL couples), but when a translocation is identified, it opens the door to preimplantation genetic testing (PGT-SR) – testing embryos created through IVF before transfer to select those unaffected by the translocation.
What’s Not Recommended
Current guidelines are equally clear about what to skip:
- Routine thrombophilia screening (Factor V Leiden, prothrombin gene mutation) is not recommended unless you have a personal history of blood clots or a strong family history of clotting disorders.
- NK cell testing and immune panels beyond APS are not supported by current evidence and are not recommended for routine RPL workup.
- TORCH serology (infections like toxoplasmosis, rubella, CMV) is not useful in RPL evaluation without specific symptoms.
Knowing what not to test for saves you money, time, and unnecessary anxiety.
When to See a Recurrent Pregnancy Loss Specialist
Your OB-GYN is a good starting point, but RPL investigation and management is a subspecialty. A recurrent pregnancy loss specialist – typically a reproductive endocrinologist (REI) – has the training to interpret these results in context, order the right tests in the right sequence, and coordinate treatment across genetics, immunology, and reproductive surgery.
The right time to make that call is now – after your second loss, before trying again. Not because something is definitely wrong, but because you deserve a complete picture before your next pregnancy begins.
What Happens If No Cause Is Found
“Unexplained RPL” is a real diagnosis, and it’s more common than most people expect. It doesn’t mean nothing can be done.
Many specialists will recommend close monitoring in early pregnancy – frequent ultrasounds and hCG checks in the first trimester – alongside emotional support and counseling. Some will discuss empirical progesterone supplementation, which the ASRM’s 2026 guidelines support in specific clinical contexts.
The data is genuinely reassuring: even without a treatable cause identified, the majority of women with two prior losses go on to have a successful pregnancy. The grief of unexplained loss is real, but the prognosis is not hopeless.
The Emotional Weight of All of This
It’s worth naming directly: going through this workup is hard. Not just logistically – the blood draws, the imaging, the waiting – but emotionally. Each test is a reminder of what you’ve lost. Each result, whether it’s an answer or another question mark, lands differently than a routine lab result would.
You’re allowed to grieve. You’re allowed to feel angry that you’re here at all. And you’re allowed to ask for support – from your partner, from a counsellor who specializes in pregnancy loss, or from community organizations like Tommy’s or the Miscarriage Association, both of which offer dedicated resources for people navigating recurrent loss.
Getting tested isn’t giving up on hope. It’s the most active, informed thing you can do to protect your next pregnancy.
