After three miscarriages, doctors typically run a panel of tests covering four main areas: chromosomal analysis of both parents, blood work for immune and clotting disorders, imaging of the uterus, and hormone screening. The goal is to find a treatable cause, which is identified in roughly 35% to 50% of cases. Many specialists now begin this workup after just two consecutive losses, since the risk of another miscarriage after two losses (24% to 29%) is close to the risk after three (31% to 33%), especially for women over 35.
Genetic Testing for Both Partners
One of the first tests ordered is a blood-based chromosomal analysis, called a karyotype, for both you and your partner. This looks for structural rearrangements in your chromosomes that don’t affect your own health but can produce embryos with too much or too little genetic material. The most common findings are balanced translocations, where segments of two chromosomes have swapped places. These show up in about 2% to 5% of couples with recurrent losses.
If a translocation is found, it doesn’t mean you can’t have a healthy pregnancy. It does mean that a higher percentage of your embryos will have chromosomal imbalances, which increases the chance of miscarriage. Knowing this information opens up options like preimplantation genetic testing during IVF, where embryos are screened before transfer.
Testing the Miscarriage Tissue Itself
If tissue from the miscarriage is available, your doctor may send it for chromosomal microarray analysis. This technique scans the DNA of the pregnancy tissue to determine whether a chromosomal abnormality caused the loss. In one large study of over 400 samples, roughly 55% of miscarriages had a detectable genetic abnormality. That’s a high proportion, and it provides genuinely useful information: if the loss was caused by a random chromosomal error in the embryo, it’s less likely to point to a recurring problem in either parent.
Microarray testing is more reliable than older methods of analyzing miscarriage tissue. Traditional cell culture techniques had failure rates as high as 21% to 25% due to contamination or tissue inactivation. Microarray works directly on DNA, avoiding those problems and catching small genetic changes that older methods miss entirely.
Blood Tests for Antiphospholipid Syndrome
Antiphospholipid syndrome (APS) is one of the most important treatable causes of recurrent miscarriage. It’s an immune condition where your body produces antibodies that increase blood clotting, which can interfere with the placenta’s blood supply. The standard screening involves three blood tests: lupus anticoagulant, anticardiolipin antibodies, and anti-beta-2 glycoprotein I antibodies.
A single positive result isn’t enough for a diagnosis. The antibodies need to be present at moderate to high levels and confirmed on a second test drawn at least 12 weeks later, because temporary spikes can happen during illness or stress. Low-level positives on their own don’t meet the diagnostic threshold. If APS is confirmed, treatment with blood-thinning medication during pregnancy significantly improves outcomes.
Uterine Imaging
Structural problems inside the uterus can cause miscarriages by disrupting implantation or blood flow to the growing pregnancy. The main conditions doctors look for are a uterine septum (a wall of tissue dividing the cavity), fibroids that protrude into the uterine lining, polyps, and scar tissue from prior procedures.
Several imaging methods can evaluate the uterine cavity. A sonohysterogram, where saline is infused into the uterus during an ultrasound, is particularly accurate. In a head-to-head comparison, sonohysterography correctly identified 100% of uterine defects confirmed by surgery, while a traditional X-ray-based test called a hysterosalpingogram accurately identified only about 46% of defects. Your doctor may also recommend hysteroscopy, where a thin camera is inserted through the cervix to directly view and sometimes treat abnormalities in the same procedure.
About half of women evaluated with sonohysterography in one study had some type of uterine abnormality detected, though not all of these require treatment.
Hormone and Metabolic Screening
Thyroid function is one of the most straightforward things to check. A blood test measuring TSH (thyroid-stimulating hormone) can reveal an underactive or overactive thyroid. Levels above 6 mIU/mL are associated with a significantly higher risk of pregnancy loss, and the risk increases by about 15% for each additional unit of elevation. Even mildly abnormal thyroid function can be corrected with medication, making this one of the most actionable findings in the workup.
Prolactin, a hormone involved in ovulation and early pregnancy support, is also measured. Elevated prolactin can disrupt the hormonal signals needed to sustain a pregnancy. Interestingly, research has found that unusually low prolactin levels may also increase miscarriage risk in women with unexplained recurrent losses.
Some doctors will screen for insulin resistance, particularly if you have risk factors like polycystic ovary syndrome or elevated BMI. Women with unexplained recurrent losses tend to have higher fasting insulin levels, and correcting insulin resistance has been shown to reduce miscarriage risk in subsequent pregnancies.
Inherited Clotting Disorders
Beyond antiphospholipid syndrome, some doctors test for inherited thrombophilias like Factor V Leiden or prothrombin gene mutations. These genetic variations make blood more prone to clotting and have been loosely associated with pregnancy loss, particularly losses that occur later in pregnancy. However, the evidence linking these conditions to early miscarriage is weaker, and major medical societies have stopped short of recommending routine screening for inherited thrombophilias in all recurrent miscarriage patients. Your doctor may still order these tests depending on your personal or family history of blood clots.
What About Sperm Testing?
Sperm DNA fragmentation testing has gained attention as a possible way to evaluate the male partner’s contribution to recurrent loss. The idea is that damaged DNA in sperm could lead to embryos that implant but fail to develop normally. However, the American Society for Reproductive Medicine, the European Society for Human Reproduction and Embryology, and the British Fertility Society have all concluded that the current evidence doesn’t support routine sperm DNA testing in clinical practice for recurrent miscarriage. It remains a research interest rather than a standard part of the workup.
When No Cause Is Found
After a complete evaluation, roughly half of couples receive no definitive explanation for their losses. This is understandably frustrating, but the prognosis for these couples is actually better than for those with an identified cause. Research shows that couples with unexplained recurrent loss are about 40% more likely to achieve a live birth in a subsequent pregnancy compared to couples where a specific problem was found. One study reported a 76% live birth rate after unexplained recurrent miscarriage, compared to 65% when a cause had been identified.
The reason for this seeming paradox is that unexplained losses are more likely to have been caused by random chromosomal errors in individual embryos, which are common and don’t necessarily repeat. An identified cause, on the other hand, tends to be something persistent that affects every pregnancy until it’s treated.