Recurrent Pregnancy Loss — Causes, Investigations & Treatment Guide — Symptoms, Causes & Treatment | MyMedicPlus

Recurrent pregnancy loss (RPL), also termed recurrent miscarriage, is defined as three or more consecutive pregnancy losses at less than 24 weeks of gestation (RCOG/ESHRE definition); the American Society for Reproductive Medicine (ASRM) uses two or more losses as the threshold. RPL is a distinct clinical entity from sporadic miscarriage — which affects 10-15% of clinically recognised pregnancies. RPL affects approximately 1-2% of couples attempting conception. Despite thorough investigation, a specific cause is identified in only 40-50% of cases — the remainder are classified as 'unexplained RPL'. This is clinically important because unexplained RPL has a surprisingly good prognosis with appropriate supportive care: 70-80% of women with unexplained RPL who receive structured 'tender loving care' (regular early pregnancy surveillance and psychological support) will achieve a successful subsequent pregnancy. RPL has profound psychological impact — anxiety, depression, and grief are universal, and psychological support is an essential component of management.

Chromosomal abnormalities: parental chromosome rearrangements (balanced translocations, inversions — present in 2-5% of couples with RPL) — these cause structurally unbalanced gametes, leading to aneuploid embryos; random fetal chromosomal abnormalities (occurring de novo in each pregnancy) account for 50-60% of sporadic and early recurrent losses, particularly in older women. Antiphospholipid syndrome (APS): the most important treatable cause — present in 5-20% of women with RPL; anticardiolipin antibodies (IgG or IgM, above 40 GPL units on two occasions 12 weeks apart), anti-beta2-glycoprotein-I antibodies, or lupus anticoagulant; APS causes placental thrombosis and infarction, leading to early pregnancy loss and late complications. Uterine anomalies: congenital (septate uterus — the most clinically relevant; bicornuate, arcuate, unicornuate) and acquired (submucous fibroids, endometrial polyps, intrauterine adhesions — Asherman's syndrome) — overall account for 10-15% of RPL. Thrombophilias: inherited thrombophilias (factor V Leiden, prothrombin G20210A mutation, protein C and S deficiency, antithrombin deficiency) — evidence for causal role in RPL is controversial; most guidelines recommend testing but treatment (heparin) is not clearly beneficial in the absence of APS. Thyroid dysfunction: hypothyroidism (TSH above 2.5 mIU/L in early pregnancy may increase RPL risk — thyroid antibodies associated with RPL even in euthyroid women). Endocrine: poorly controlled diabetes mellitus; luteal phase deficiency (controversial). Immune factors: natural killer cell abnormalities (elevated uterine NK cells in endometrial biopsy) — unproven treatment targets. Risk factors: advancing maternal age (age above 35 increases both RPL risk and chromosomal loss risk substantially); obesity (BMI above 30 — 30% higher RPL risk); smoking; alcohol; and male factor (sperm DNA fragmentation — increasingly recognised).

Recurrent pregnancy loss is characterised by recurrent episodes of: vaginal bleeding in early pregnancy (implantation bleeding must be distinguished from miscarriage bleeding); cramping lower abdominal pain accompanying bleeding; passage of products of conception; and a non-viable pregnancy on early ultrasound (no fetal heartbeat, irregular gestational sac, or embryo/fetal demise). First-trimester loss (before 12 weeks) is the most common pattern — associated with chromosomal, uterine, and APS causes. Second-trimester loss (12-24 weeks) raises different differential diagnoses — cervical incompetence (painless cervical dilatation), uterine anomaly, or late APS manifestations. Women with RPL may also experience: subfertility and prolonged time to conception; symptoms of hypothyroidism (fatigue, weight gain, cold intolerance) if thyroid disease is contributory; and features of SLE or APS (thrombosis, livedo reticularis, thrombocytopaenia) in those with antiphospholipid syndrome. Psychological consequences — anxiety, depression, grief, relationship difficulties, and post-traumatic stress — are universal and may be more prominent than physical symptoms.

Investigations recommended by ESHRE 2022 RPL Guidelines: Antiphospholipid antibodies: lupus anticoagulant, anticardiolipin IgG/IgM, anti-beta2-glycoprotein-I IgG/IgM — all must be positive on two occasions at least 12 weeks apart to diagnose APS. Parental karyotype: peripheral blood karyotyping of both partners — identifies balanced chromosomal rearrangements in 2-5% of couples; if identified, IVF with PGT-A (preimplantation genetic testing for aneuploidy) can improve live birth rates significantly. Uterine anatomy assessment: 3D transvaginal ultrasound (TV3DUS) — the recommended first-line investigation for uterine anomalies; hysteroscopy for definitive assessment and concurrent surgical treatment of uterine septum or intrauterine adhesions. Thyroid function tests (TSH, free T4) and thyroid peroxidase antibodies (TPO Ab) — even in clinically euthyroid women. Luteal phase assessment: mid-luteal progesterone or serum progesterone in the first trimester. Blood glucose/HbA1c: in women with diabetes risk factors. Additional tests of uncertain benefit (not routinely recommended in most guidelines but offered in specialist centres): inherited thrombophilia screen (factor V Leiden, prothrombin mutation, protein C/S, antithrombin); sperm DNA fragmentation; uterine NK cell assessment; immunological testing (HLA-G, alloimmune antibodies). Histological and cytogenetic analysis of products of conception: recommended after each loss — identifies chromosomal cause (supporting expectant management for the specific pregnancy) and provides prognostic information.

Antiphospholipid syndrome: low-dose aspirin (75-150 mg daily from pre-conception or positive pregnancy test) PLUS low-molecular-weight heparin (LMWH — enoxaparin 40 mg SC daily or dalteparin 5000 IU SC daily from positive pregnancy test through to 34-36 weeks) — the PROMISE trial and subsequent studies confirm this combination reduces miscarriage rates from approximately 50-70% to 25-30% in APS. Thrombophilia without APS: LMWH is NOT recommended routinely — meta-analyses show no benefit for inherited thrombophilia without confirmed APS. Uterine septum: hysteroscopic metroplasty (resection of the septum) — observational data suggest improvement in live birth rates; a randomised controlled trial (TRUST) showed no significant benefit over expectant management, but hysteroscopy is still widely offered given the low risk and possible benefit. Intrauterine adhesions: hysteroscopic adhesiolysis. Submucosal fibroids: hysteroscopic myomectomy. Thyroid: treat hypothyroidism to maintain TSH below 2.5 mIU/L; levothyroxine in euthyroid women with positive TPO antibodies may reduce RPL (TABLET trial showed no benefit; ongoing debate). Progesterone: vaginal progesterone (400 mg twice daily or 200-400 mg nocte) started in the first trimester — the PRISM trial (n=4153) demonstrated a 3% absolute increase in live birth rate in women with previous RPL and early pregnancy bleeding, and up to 5% benefit in those with 3+ losses; now recommended by RCOG. Chromosomal causes: IVF with preimplantation genetic testing for aneuploidy (PGT-A) or structural chromosomal rearrangements (PGT-SR) — reduces miscarriage rate per transfer but may not improve cumulative live birth rate over expectant management; avoids aneuploid embryo transfers. Unexplained RPL: 'tender loving care' — regular early pregnancy ultrasound surveillance (fortnightly from 6 weeks), psychological support, and reassurance achieves 70-80% live birth rates, often without any specific intervention.

Recurrent pregnancy loss carries significant physical, psychological, and fertility-related complications. Psychological impact: RPL is profoundly traumatic — depression affects approximately 40–60% of women experiencing three or more consecutive losses; anxiety (including intense anticipatory anxiety in subsequent pregnancies) is nearly universal; PTSD symptoms following miscarriage are documented in a significant proportion of women; grief responses are often prolonged and socially underacknowledged (disenfranchised grief); relationship strain, sexual dysfunction, and social withdrawal are common consequences requiring proactive support. Uterine complications from repeated surgical evacuation: intrauterine adhesions (Asherman's syndrome) can develop after repeated surgical management of miscarriage — causes menstrual abnormalities (hypomenorrhoea, amenorrhoea), secondary infertility, and further pregnancy loss; diagnosis is by hysteroscopy; treatment is hysteroscopic adhesiolysis. Haemorrhagic complications: significant haemorrhage requiring blood transfusion occurs in approximately 1–2% of miscarriage episodes; emergency surgical evacuation or uterine artery embolisation may be required. Rh sensitisation: Rh-negative women who do not receive anti-D immunoglobulin after miscarriage risk developing antibodies causing haemolytic disease of the newborn in future pregnancies. Septic miscarriage: retained products of conception (RPOC) from incomplete expulsion cause ascending uterine infection, which can progress to septicaemia and septic shock if untreated. Antiphospholipid syndrome complications: the most common treatable cause (found in 15–20% of RPL patients) carries independent systemic risks — venous thromboembolism (DVT, pulmonary embolism) and arterial thrombosis (stroke, MI) — requiring long-term anticoagulation and specialist haematology or rheumatology follow-up beyond the obstetric setting.

Lifestyle optimisation significantly improves outcomes in RPL. Weight loss: obesity (BMI above 30) is associated with 30% higher RPL risk — achieving BMI below 30 before attempting pregnancy improves outcomes and response to treatment. Smoking cessation: cigarette smoking is associated with increased RPL risk (possibly through fetal placental hypoxia and cytogenetic effects on gametes). Alcohol avoidance: moderate alcohol intake is associated with increased miscarriage risk — complete abstinence is recommended in early pregnancy. Folic acid supplementation (400 mcg daily — 5 mg in high-risk groups such as previous neural tube defect) from pre-conception through 12 weeks reduces neural tube defects and may reduce some chromosomal losses. Vitamin D sufficiency: emerging evidence links vitamin D deficiency with increased RPL risk; supplementation with 1000-2000 IU daily is safe in pregnancy and generally recommended. Psychological support: specialist recurrent miscarriage clinics with nurse counsellors or psychologists significantly improve wellbeing and perceived outcomes; cognitive behavioural therapy and peer support groups are valuable.

Seek medical review after any second miscarriage — do not wait for a third before requesting investigation. ASRM now recommends investigation after two consecutive losses; ESHRE after three. Make an urgent same-day appointment or attend emergency gynaecology if you have: heavy vaginal bleeding (soaking pads); severe lower abdominal pain; passage of tissue; or symptoms of septic miscarriage (fever, rigor, offensive discharge — requires immediate assessment). Request referral to a specialist recurrent miscarriage clinic after a second or third miscarriage — these clinics provide structured investigation (antiphospholipid screen, karyotyping, uterine imaging), ongoing psychological support, and early pregnancy surveillance to achieve the best possible outcome. Do not accept 'it is just bad luck, try again' as the only response after multiple losses — specialist assessment is warranted and effective.