Antiphospholipid syndrome (APS or APLS) or antiphospholipid antibody syndrome is a disorder of coagulation that causes blood clots (thrombosis) in both arteries and veins as well as pregnancy-related complications such as miscarriage, stillbirth, preterm delivery, or severe preeclampsia. The syndrome occurs due to the autoimmune production of antibodies against phospholipid (aPL), a cell membrane ...