Recurrent Pregnancy Loss Evaluation: Every Test and What It Means

Losing a pregnancy once is common and usually requires no investigation. Losing two or more changes the clinical picture. Recurrent pregnancy loss (RPL) affects 1 to 2% of couples trying to conceive, and while the emotional weight is enormous, the medical workup is methodical. There are specific tests, done in a specific order, that either identify a treatable cause or narrow the field to "unexplained" with a still-favorable prognosis.

This guide walks through the full evaluation, what each test looks for, and what the results change about your plan going forward.

When to Start the Evaluation

The American Society for Reproductive Medicine (ASRM) recommends evaluation after two clinical pregnancy losses. A clinical loss means a pregnancy confirmed by ultrasound or rising hCG, not a chemical pregnancy. That said, many reproductive endocrinologists will start the workup after a single loss if you are over 35, have a limited reproductive timeline, or have additional risk factors.

The Testing Layers

The RPL workup covers five broad domains. Not every patient needs every test, but most evaluations touch all five.

Layer 1: Chromosomal Analysis

This is the single most informative category. Roughly 50 to 60% of first-trimester losses are chromosomally abnormal. The key question is whether these represent random bad luck (aneuploid eggs or sperm) or a structural rearrangement in one parent that systematically produces unbalanced embryos.

Parental karyotyping is a blood test for both partners. About 3 to 5% of RPL couples have a balanced translocation or inversion in one partner that produces chromosomally unbalanced embryos at a high rate. This finding changes the plan significantly, often toward IVF with PGT for structural rearrangements (PGT-SR).

Layer 2: Uterine Anatomy

A uterine septum is the most common treatable structural finding, present in roughly 3 to 5% of women with RPL. A septum has poor blood supply and may prevent proper implantation or placental development. Hysteroscopic septum resection is a relatively straightforward procedure with strong evidence for reducing subsequent loss rates.

Other structural findings include fibroids (particularly submucosal ones that distort the cavity), polyps, and Asherman syndrome (intrauterine adhesions, sometimes from prior D&C procedures). A saline infusion sonogram (SIS) or office hysteroscopy is the standard screening tool.

Layer 3: Hormonal and Metabolic

Thyroid dysfunction is the most actionable finding here. Both overt and subclinical hypothyroidism have been associated with pregnancy loss, and treatment with levothyroxine is simple and effective. Most experts recommend a TSH below 2.5 mIU/L for conception, though the optimal target is debated.

Uncontrolled diabetes increases miscarriage risk. An HbA1c is worth checking even without a prior diagnosis, particularly if PCOS or insulin resistance is suspected. Prolactin elevation, while less common, can disrupt progesterone support of early pregnancy.

Layer 4: Thrombophilia

Antiphospholipid syndrome (APS) is the most evidence-backed clotting disorder in RPL. The diagnostic criteria require both clinical findings (pregnancy losses or blood clots) and positive laboratory tests on two occasions at least 12 weeks apart. The antibodies tested include:

• Lupus anticoagulant
• Anticardiolipin antibodies (IgG and IgM)
• Anti-beta-2 glycoprotein I antibodies (IgG and IgM)

When APS is confirmed, treatment with low-dose aspirin and heparin during pregnancy has been shown to significantly improve live birth rates. This is one of the strongest treatment-to-outcome stories in RPL management.

Layer 5: Immunological

Beyond APS, the role of the immune system in RPL is an area of active research and some controversy. Natural killer (NK) cell testing, cytokine panels, and HLA typing are offered by some clinics but are not part of standard ASRM guidelines. The evidence for immune-modulating treatments (intralipid infusions, IVIG, steroids) in unexplained RPL remains insufficient for routine recommendation.

When No Cause Is Found

In 25 to 50% of RPL evaluations, all tests come back normal. This is genuinely frustrating, but the prognosis is actually better than it sounds. Couples with unexplained RPL have a 60 to 75% chance of a successful next pregnancy with supportive care alone, which typically includes early monitoring, progesterone supplementation, and more frequent ultrasounds for reassurance.

Some clinics offer empiric treatments (aspirin, progesterone, or low-molecular-weight heparin) for unexplained RPL on a "low risk, possible benefit" basis. The evidence for each is mixed, but the safety profile is generally acceptable.

Emotional Support Is Part of the Workup

The emotional toll of recurrent loss is real and cumulative. Studies have found that women with RPL experience anxiety and depression at rates comparable to those diagnosed with other significant health conditions. Supportive care, whether through therapy, support groups, or simply consistent clinical attention, is associated with better pregnancy outcomes in subsequent attempts, independent of medical treatment.