Antiphospholipid antibody syndrome

Lupus Foundation of America

Resource Content

APS is a blood disorder where your body accidentally attacks normal proteins in the blood, which are made to control blood clotting. A person with APS has antiphospholipid antibodies. These antibodies cause blood clots to form. This leads to several complications, including:

  • Blood clots in veins: DVT (deep vein thrombosis)
  • Blood clots in arteries: strokes and heart attacks
  • Miscarriages
  • Low platelet count (thrombocytopenia)


At least one clinical plus one laboratory criteria must be present for a person to be classified as having APS

Clinical Criteria
  • Vascular thrombosis (blood clot in the vessel)
  • Pregnancy morbidity: One or more unexplained deaths of a normal fetus after at least 10 weeks of gestation OR before the 34th week of gestation due to preeclampsia (high blood pressure), eclampsia (seizures/coma), or placental insufficiency(placenta can’t support the baby), OR 3 or more unexplained miscarriages (spontaneous abortions) before the 10th week of gestation
Laboratory criteria
  • IgG or IgM isotype anticardiolipin antibodies on two occasions at least three months apart
  • Lupus anticoagulant on two occasions at least six weeks apart


Treatment varies depending on whether a person with lupus has a history of blood clotting or not. If you have a history of blood clotting, your doctor may ask you to:

  • Take a blood thinning medication such as warfarin, sometimes with baby aspirin added

If you do not have a history of abnormal blood clotting, your doctor may ask you to:

  • Take baby aspirin daily
  • Take hydroxychloroquine
  • Stop oral contraceptives and hormone replacement therapy

APS and pregnancy

It is possible that a woman with APS may experience pregnancy complications.

Problems that occur if a woman with APS gets pregnant include:
  • Miscarriage
  • Preeclampsia (high blood pressure in a pregnant woman)
  • Premature birth

There are certain medications that lower the risk of miscarriages for woman with APS.

If you have a past of miscarriages, medications include:
  • Aspirin (always speak with your doctor before taking this)
  • Heparin injections
If you do not have a past of miscarriages or are pregnant for the first time:
  • Your doctor may recommend daily baby aspirin or
  • no treatment of any kind

Pregnant women with antiphospholipid antibodies as well as their babies should always be monitored. Throughout the pregnancy, ultrasounds can track the placenta and its blood flow to assure the baby is healthy. Towards the end of pregnancy, blood pressure should be frequently monitored in case of preeclampsia.

Medically reviewed on