Antiphospholipid syndrome (APS) is an acquired autoimmune disorder in which the immune system mistakenly produces antiphospholipid antibodies that attack tissues in the body. These antibodies can lead to the formation of blood clots in arteries and veins. During pregnancy, APS can also lead to miscarriage and stillbirth. Classification criteria require a clinical event (i.e., thrombosis or pregnancy complication) and persistent positive blood test...