Version July 2025
| Clinical setting | Antepartum | Postpartum |
| Thrombotic APS with or without obstetric APS* | Therapeutic-dose LMWH and LDA | Transition back to warfarin (safe for breastfeeding). Continue LDA if patient was taking it prepregnancy. |
| Obstetric APS¶ | Prophylactic-dose LMWH and LDA | Continue prophylactic-dose LMWH and LDA for six weeks postpartum |
| Persistent aPL with history of adverse pregnancy outcome but not meeting APS-defining criteriaΔ | LDA | Vaginal birth: Continue LDA for six weeks postpartum Cesarean birth: Continue LDA and add prophylactic-dose LMWH for six weeks postpartum |
aB2GPI: anti-beta 2 glycoprotein I; aCL: anticardiolipin antibody; aPL: antiphospholipid antibodies; APS: antiphospholipid syndrome; IgG: immunoglobulin G; IgM: immunoglobulin M; IVF: in vitro fertilization; LA: lupus anticoagulant; LDA: low-dose aspirin; LMWH: low molecular weight heparin; SC: subcutaneous; SLE: systemic lupus erythematosus.
* All patients should meet laboratory criteria for aPL or APS (positive LA and/or moderate-high titer aCL or anti-beta2GPI IgG or IgM).
¶ APS classification criteria are not diagnostic criteria. The clinical decision to proceed with therapy when classification criteria are not met but clinical obstetric APS is suspected should be based on the patient's clinical risk profile and personal preferences.
Δ In rare circumstances where patients have a high-risk aPL laboratory profile and a high-risk clinical scenario (eg, first pregnancy in the setting of advanced maternal age, infertility with need for IVF, and/or underlying SLE), discuss low-dose ASA and LMWH therapy and assess risk/benefits for the individual patient's situation.
Patients with lower-titer or IgA isotypes of aCL/anti-beta2GPI, or non-criteria aPL who do not meet laboratory classification criteria may still have some degree of risk that is difficult to quantify. Decisions regarding therapy in these cases rest on discussion between the patient and the physician, considering additional relevant clinical risk factors.
Examples of therapeutic LMWH (also referred to as weight-adjusted, full-treatment dose) include: enoxaparin 1 mg/kg every 12 hours, dalteparin 200 units/kg once daily, tinzaparin 175 units/kg once daily, dalteparin 100 units/kg every 12 hours.
Examples of prophylactic LMWH include: enoxaparin 40 mg SC once daily, dalteparin 5000 units SC once daily, tinzaparin 4500 units SC once daily. These doses may need to be modified at extremes of body weight.
Anticoagulation can generally be resumed 4 to 6 hours after vaginal delivery or 6 to 12 hours after cesarean birth, unless there is significant bleeding or risk for significant bleeding. Previous neuraxial anesthesia is also a consideration (eg, anticoagulation may be resumed 4 or more hours after catheter removal unless traumatic placement).
Note: Tinzaparin is not available in the United States. The role and frequency of anti-Xa testing for management of therapeutic dosing of LMWH in pregnancy are reviewed in the UpToDate topic on anticoagulation in pregnancy. LDA doses range from 75 to 180 mg daily depending on locally available doses. In the United States, one or two 81 mg tablets daily is a common dose.
