Recurrent Pregnancy Loss: Unexplained After Basic Workup
A 34-year-old woman, G4P0, presents with a history of three consecutive first-trimester miscarriages at 8, 9, and 10 weeks. She has no living children. She has regular cycles, BMI 23, and no medical history. Her partner is 36 and healthy. They are non-smokers. Karyotyping of the products of conception from the last miscarriage showed a normal female karyotype. She has had a full thrombophilia screen (including antiphospholipid antibodies on two occasions), thyroid function tests, and a pelvic ultrasound, all normal. She feels frustrated and asks, 'Why is this happening? What else can we do?'
1. What is the definition of recurrent pregnancy loss (RPL) and what is the recommended investigation protocol?
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Definition: Recurrent pregnancy loss is traditionally defined as three or more consecutive miscarriages, though some organisations use two or more. It affects 1–2% of couples.
Investigations (after two or three losses):
- Antiphospholipid syndrome (APS): Test for lupus anticoagulant, anticardiolipin antibodies, and anti-β2 glycoprotein I antibodies on two occasions at least 12 weeks apart. (Already done and normal.)
- Parental karyotyping: Offered if products of conception show unbalanced chromosomal abnormalities or if there is a history of congenital anomalies. Not routinely needed if products of conception are normal, but can be considered.
- Uterine anatomy: Transvaginal ultrasound, hysteroscopy, or saline infusion sonography to exclude septate uterus, fibroids, polyps, or adhesions. (Ultrasound normal, but consider hysteroscopy if clinically indicated.)
- Thyroid function and diabetes: TSH and HbA1c. (TSH normal.)
- Thrombophilia screening: Not routinely recommended unless personal or family history of thrombosis. (Already done.)
- Lifestyle: Advise on smoking, alcohol, caffeine, and weight. (Already healthy.)
- Endometrial receptivity array (ERA) or other tests: Not routinely recommended; evidence limited.
In this case, the workup is essentially normal, so the diagnosis is unexplained RPL. Further investigations may include hysteroscopy to exclude a uterine septum (not seen on ultrasound) and possibly parental karyotyping if not done. But routine karyotyping is not mandatory if products of conception are normal.
2. What is the evidence for empirical treatments in unexplained RPL, and how would you counsel this couple about their prognosis and options?
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Evidence for empirical treatments:
- Progesterone supplementation: The PROMISE trial showed no benefit of first-trimester progesterone in unexplained RPL, though a subgroup analysis suggested possible benefit in women with three or more losses. The PRISM trial found no overall benefit but a possible benefit in women with early pregnancy bleeding. Routine use is not recommended, but some clinicians offer it.
- Low-dose aspirin and heparin: Only effective in antiphospholipid syndrome; no benefit in unexplained RPL.
- Intravenous immunoglobulin (IVIG) and paternal leukocyte immunization: Not recommended; evidence insufficient and risks.
- Metformin: No evidence in unexplained RPL.
- Preimplantation genetic testing for aneuploidy (PGT-A): Controversial; may reduce miscarriage rate in women with advanced maternal age but not proven for RPL.
- Lifestyle: Encourage healthy diet, avoid smoking/alcohol, and consider folic acid supplementation.
Prognosis: Even after three unexplained losses, the chance of a successful live birth in a subsequent pregnancy is approximately 50–60%, and often higher with supportive care. Age is a major factor; at 34, ovarian reserve should be considered (AMH, antral follicle count).
Counselling:
- Explain that in many cases no cause is found, and the next pregnancy has a good chance of success.
- Offer early ultrasound scan (at 6–7 weeks) for reassurance.
- Discuss referral to a specialist RPL clinic for further evaluation (e.g., hysteroscopy, parental karyotyping) if not already done.
- Address psychological support; RPL can cause significant anxiety and depression.
- Discuss options including expectant management, progesterone supplementation (if desired after informed discussion), and consideration of IVF with PGT-A if appropriate, though evidence is limited.
- Emphasise that the couple should not blame themselves.