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Educational draft · awaiting clinical reviewUse Rapid for revision, not patient-care decisions. Check current national and local guidance and the BNF or BNFC before acting.

Recurrent pregnancy loss investigation

Obstetrics and gynaecology · UK scope · Sources checked 27 Aug 2026 · Clinical review pending

RapidFull
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Assess the current pregnancy separately

A history of recurrent loss does not make new bleeding automatically another miscarriage and does not exclude ectopic pregnancy, haemorrhage or sepsis.

Action: If the patient is pregnant now, assess stability, pain, bleeding and pregnancy location through the acute early-pregnancy pathway before arranging the longer-term recurrent-loss work-up.

Synopsis

Build a targeted recurrent-loss evaluation that finds actionable antiphospholipid, genetic, uterine and endocrine factors while avoiding unvalidated panels and blame.

  • RCOG defines recurrent miscarriage as three or more first-trimester miscarriages; they need not be consecutive or with the same partner.
  • Use clinical discretion to investigate after two first-trimester losses when their pattern suggests pathology rather than independent sporadic events.
  • Start with a verified pregnancy timeline, maternal and paternal age, gestations, ultrasound or histology findings, complications, conditions, medicines, family history and lifestyle.
  • Core tests include antiphospholipid antibodies, thyroid function with thyroid peroxidase antibodies, and pelvic ultrasound to assess uterine anatomy.
  • Confirm antiphospholipid syndrome with persistent qualifying antibodies on two samples at least 12 weeks apart and at least 6 weeks after miscarriage.
  • Offer cytogenetic testing of pregnancy tissue from the third and subsequent miscarriage; parental karyotyping is selected by tissue results or inability to obtain an informative result.
  • Do not routinely order inherited thrombophilia panels, natural-killer-cell assays, HLA or cytokine tests, infection screens or sperm DNA fragmentation for recurrent first-trimester loss.
  • Confirmed obstetric APS is treated in pregnancy with low-dose aspirin plus heparin; do not give either empirically for unexplained recurrent miscarriage.
  • Progesterone is not routine prophylaxis while asymptomatic, but NICE offers vaginal micronised progesterone 400 mg twice daily for scan-confirmed intrauterine pregnancy with bleeding and any previous miscarriage.

    • Key red flags

    Current severe pain, syncope, shoulder-tip pain, peritonism or haemodynamic compromise requiring emergency ectopic assessment.

    Current heavy bleeding, fever, offensive discharge or systemic illness suggesting haemorrhage or infected miscarriage.

    Previous second-trimester painless cervical dilatation, membrane rupture or very preterm birth suggesting cervical insufficiency and future specialist planning.

    Personal thrombosis, systemic lupus features or previous severe placenta-mediated disease raising concern for antiphospholipid syndrome.

    Severe depression, trauma symptoms, inability to function, self-harm thoughts or immediate safeguarding concerns after repeated losses.

    Investigation priorities

    01
    Antiphospholipid antibody panelFirst step

    Detect an acquired, treatable thrombophilia associated with recurrent and later pregnancy loss.

    Management branches

    Referral and baseline work-upVerify the phenotype before testing

    There are three first-trimester miscarriages, an eligible later loss, or two early losses with features suggesting pathology.

    1. Reconstruct every pregnancy with records where available and take medical, obstetric, thrombotic, genetic, medication, family, social and reproductive histories.
    2. Offer APS testing, thyroid function with TPO antibodies and uterine ultrasound, then arrange pregnancy-tissue or parental genetic testing according to the loss number and available specimen.
    3. Screen emotional wellbeing and safety, discuss modifiable associations without blame, and agree how results and future-pregnancy access will be communicated.

    Key medicines

    Low-dose aspirin plus heparin for confirmed obstetric APSUse a specialist pregnancy plan: low-dose aspirin 75 to 150 mg orally once daily plus prophylactic unfractionated heparin or weight-adjusted low-molecular-weight heparin by subcutaneous injection; exact start, product, dose and stop timing depend on APS, thrombosis history, weight and delivery plan.Do not use for a single transient antibody result or unexplained recurrent miscarriage; assess bleeding, ulcer, aspirin sensitivity, renal function, platelet count, previous heparin-induced thrombocytopenia, neuraxial timing and peripartum interruption with obstetric and haematology teams.
    Vaginal micronised progesteroneOffer 400 mg vaginally twice daily when ultrasound confirms an intrauterine pregnancy and early-pregnancy bleeding occurs after at least one previous miscarriage; if a fetal heartbeat is confirmed, continue until 16 completed weeks.Do not use progesterone to bypass assessment of pregnancy location, viability, ectopic symptoms or haemodynamic danger; explain local irritation, discharge, headache and the defined stopping point.
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    Sources and review status4 sources · checked 27 Aug 2026 · clinical review pending+
    Sources

    Sources and review status

    National guidance is shown before implementation-dependent detail. Typical adult dose examples remain subject to patient factors, contraindications and the live BNF or specialist protocol. Source check completed 27 Aug 2026; clinical approval remains outstanding.

    • RCOG Green-top Guideline 17Current definition, investigation principles, treatment and supportive care.
    • RCOG recurrent miscarriage informationAccessible explanation of causes, APS confirmation, testing and treatment limits.
    • NICE NG126 miscarriage managementExact progesterone eligibility, dose and continuation threshold.
    • NICE NG3 diabetes before pregnancyPreconception and pregnancy management for diabetes when it is a relevant factor.

    Editorial contact: Doctor’s Passport editorial team. Source-check date is separate from clinical approval. Report a content problem · Content changes

    Authoring stateRapid draftClinical stateAwaiting reviewJurisdictionUnited Kingdom