Antiphospholipid Antibody Syndrome in Pregnancy Antiphospholipid antibody syndrome (APS) is an autoimmune disorder that predisposes patients to thrombosis and, during pregnancy, increases risk of Fetal demise Pregnancy-induced hypertension Preeclampsia Intrauterine growth restriction APS is caused by autoantibodies to certain phospholipid-binding proteins that would otherwise protect against excessive coagulation activation.