For clinicians

Antiphospholipid syndrome (APS)

APS, antiphospholipid antibodies, Hughes syndrome

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Bottom lineBottom line: obstetric APS is managed with low-dose aspirin plus prophylactic heparin/LMWH, which substantially improves live-birth rates. Thrombotic APS requires therapeutic anticoagulation with warfarin switched to LMWH before or early in pregnancy. Risk-stratify by antibody profile and history; co-manage with maternal-fetal medicine.

By domain

Will APS affect the pregnancy? ●●●○moderate evidencestrong

Associated with recurrent early loss, fetal death, pre-eclampsia, and placental insufficiency/IUGR. Risk is strongly antibody-profile-dependent. In the PREGNANTS retrospective cohort (750 singleton primary-APS pregnancies, all on low-dose aspirin plus prophylactic LMWH from the first trimester), the overall live-birth rate was 54.3% (407/750), ranging from 30% in triple-positive women to 79.6% with lupus anticoagulant alone (aCL alone 56.3%, anti-b2GPI alone 47.7%, double-positive 43.3%). Multiple-antibody positivity vs single: 40.9% vs 56.6% (aOR 0.71, 95% CI 0.51-0.90). Prior vascular thrombosis lowered live birth (42.0% vs 56.6% without). This cohort is retrospective, primary-APS-only, singleton-only, and enriched for prior thrombosis, so its overall rate sits at the more severe end of the literature.[1, 3, 6]

Treatment in pregnancy ●●●○moderate evidencestrong

Obstetric APS: low-dose aspirin plus prophylactic heparin/LMWH. Thrombotic APS: therapeutic anticoagulation; convert warfarin to LMWH pre-conception or by early pregnancy. In aPL-positive patients who do NOT meet criteria for obstetric or thrombotic APS, ACR 2020 conditionally recommends prophylactic low-dose aspirin (81-100 mg daily) alone and recommends against adding prophylactic heparin or prophylactic hydroxychloroquine for that indication. BSR 2023 (part 2) cites a systematic review of 22 RCTs (LDA plus heparin in APS) showing significantly improved adverse pregnancy outcomes; it does not provide a single pooled live-birth percentage.[1, 2, 4, 5]

Planning ahead ●●○○low evidenceconditional

Confirm antibody profile and classification; individualise the aspirin/heparin plan; plan warfarin-to-LMWH transition; add hydroxychloroquine in refractory or SLE-associated cases.[1, 3]

If standard treatment is not enough ●●●○moderate evidencestrong

ACR 2020 strongly recommends AGAINST adding prednisone to prophylactic-dose heparin/LMWH plus low-dose aspirin in refractory obstetric APS (verified, primary text). It conditionally recommends adding hydroxychloroquine. IVIG is used rarely, with limited evidence.[1]

Monitoring in pregnancy ●●○○low evidenceconditional

Serial growth and uterine artery Doppler surveillance; monitor for pre-eclampsia; obstetric-medicine co-management.[1]

After birth ●●●○moderate evidencestrong

Elevated postpartum thrombosis risk: continue anticoagulation per plan (often 6 weeks or long-term in thrombotic APS). Avoid estrogen-containing contraception.[1]

Key points

PointEvidence
Aspirin plus prophylactic LMWH is the evidence-based standard for obstetric APS.[1]●●●○moderate evidencestrong
Estrogen-containing contraception is contraindicated with antiphospholipid antibody positivity.[1]●●●○moderate evidencestrong

Key numbers

References

  1. Sammaritano LR, et al. 2020 ACR Guideline for the Management of Reproductive Health in RMD. Arthritis Rheumatol. 2020;72(3):529-556. https://acrjournals.onlinelibrary.wiley.com/doi/10.1002/art.41191
  2. Ruegg L, et al. EULAR recommendations for antirheumatic drugs in reproduction, pregnancy, and lactation: 2024 update. Ann Rheum Dis. 2025;84(6):910-926. https://ard.eular.org/article/S0003-4967(25)00818-0/fulltext
  3. Tarter L, Bermas BL. Expert Perspective: Lupus and Pregnancy. Arthritis Rheumatol. 2024;76(3):321-331. https://acrjournals.onlinelibrary.wiley.com/doi/10.1002/art.42756
  4. Guideline Central summary of the 2020 ACR Guideline for the Management of Reproductive Health in Rheumatic and Musculoskeletal Diseases (recommendation strengths for SLE, aPL, and APS). https://www.guidelinecentral.com/guideline/7066/
  5. Schreiber K, Frishman M, Russell MD, et al. British Society for Rheumatology guideline on prescribing drugs in pregnancy and breastfeeding: comorbidity medications used in rheumatology practice. Rheumatology (Oxford). 2023;62(4):e89-e104. https://doi.org/10.1093/rheumatology/keac552
  6. Saccone G, Berghella V, Maruotti GM, et al. Antiphospholipid antibody profile based obstetric outcomes of primary antiphospholipid syndrome: the PREGNANTS study. Am J Obstet Gynecol. 2017;216(5):525.e1-525.e12. https://doi.org/10.1016/j.ajog.2017.01.026