Anticoagulation Therapy in Pregnant Patients with Antiphospholipid Syndrome

Introduction to Antiphospholipid Syndrome

Pregnant patients with antiphospholipid syndrome (APS) should receive anticoagulation therapy when they meet BOTH laboratory criteria (persistent antiphospholipid antibodies) AND clinical criteria (either three or more pregnancy losses OR history of thrombosis), as recommended by the American College of Chest Physicians 1, 2, 3

The patient must fulfill laboratory criteria for antiphospholipid antibody (APLA) syndrome, which requires persistent positivity of one or more of the following on two separate occasions at least 12 weeks apart: Lupus anticoagulant (LAC), Anticardiolipin antibodies (IgG or IgM), or Anti-beta-2-glycoprotein I antibodies (IgG or IgM), according to the American College of Rheumatology 1, 2, 3
Lupus anticoagulant (LAC) conveys the greatest risk for adverse pregnancy outcomes (RR 12.15) 2, 3

Three or more pregnancy losses (recurrent early pregnancy loss before 10 weeks of gestation) is a threshold that triggers strong recommendation for treatment, as recommended by the American College of Chest Physicians 1, 2, 4, 5
History of prior thrombotic events (venous, arterial, or microvascular thrombosis) requires treatment with low-dose aspirin combined with therapeutic-dose heparin (usually LMWH) throughout pregnancy and postpartum, according to the American College of Rheumatology 2, 3

For obstetric APS, the standard treatment is LMWH at prophylactic or intermediate doses plus low-dose aspirin 75-100 mg daily, with a Grade 1B recommendation, as suggested by the American College of Chest Physicians 1, 4, 6
For thrombotic APS, the treatment is LMWH at therapeutic doses (or 75% of therapeutic dose) plus low-dose aspirin, continued throughout pregnancy and postpartum, according to the American College of Rheumatology 2, 3, 5
Hydroxychloroquine (HCQ) may be added to standard therapy in patients with primary APS, with a conditional recommendation, as suggested by the American College of Rheumatology 2, 6

Asymptomatic aPL-positive patients without clinical criteria do NOT routinely receive prophylactic anticoagulation to prevent pregnancy loss, but should receive only prophylactic aspirin 81-100 mg daily for preeclampsia prophylaxis, as recommended by the American College of Rheumatology 2, 3
Patients with only two miscarriages without APLA or thrombophilia should NOT receive antithrombotic prophylaxis, with a Grade 1B recommendation against treatment, as suggested by the American College of Chest Physicians 1, 4
Vitamin K antagonists should be avoided in the first trimester (teratogenic risk) and from week 36 onwards (risk of fetal intracranial bleeding), according to the American College of Chest Physicians and the European Society of Cardiology 1, 4, 7
Direct oral anticoagulants are contraindicated during pregnancy due to safety concerns, as recommended by the American College of Chest Physicians and the European Society of Cardiology 7, 8

In pregnant women with antiphospholipid syndrome experiencing antepartum bleeding, low molecular weight heparin (LMWH) should be temporarily discontinued at least 24 hours before any planned intervention, but resumed as soon as hemostasis is achieved, as the American College of Chest Physicians recommends, due to the high risk of thrombosis and pregnancy loss associated with untreated antiphospholipid syndrome 9, 10

For obstetric antiphospholipid syndrome, defined as three or more pregnancy losses before 10 weeks or one or more unexplained losses after 10 weeks, prophylactic-dose LMWH plus low-dose aspirin is recommended (Grade 1B) by the American College of Chest Physicians 9, 10
For thrombotic antiphospholipid syndrome, characterized by a history of thrombosis, therapeutic-dose LMWH plus low-dose aspirin is recommended throughout pregnancy, as suggested by the American College of Rheumatology 11

The American College of Chest Physicians recommends discontinuing LMWH immediately if bleeding is moderate to severe, and continuing low-dose aspirin unless bleeding is life-threatening, to minimize the risk of thrombosis and pregnancy loss 9, 10, 11

Before cerclage placement, LMWH should be stopped at least 24 hours before the procedure to minimize bleeding risk, and resumed 6-12 hours after the procedure once hemostasis is confirmed, as recommended by the American College of Chest Physicians (Grade 1B) 9, 10

The American College of Chest Physicians recommends resuming prophylactic-dose LMWH within 12-24 hours after bleeding stops or after a procedure, to minimize the risk of thrombosis and pregnancy loss 9, 10
For thrombotic antiphospholipid syndrome, therapeutic-dose LMWH should be resumed after bleeding stops or after a procedure, as recommended by the American College of Rheumatology 11

The American College of Chest Physicians recommends continuing anticoagulation for at least 6 weeks postpartum (Grade 2B) to minimize the risk of thrombosis 9, 10