Anti-cardiolipin antibodies are not a mandatory test for pregnancy, but are usually tested for women with a history of embryonic abruption or recurrent miscarriage. Anti-cardiolipin antibodies are autoimmune antibodies that target cardiolipin as an antigen and act on platelets and endothelial cells. Anti-cardiolipin antibodies are not a mandatory test for pregnancy, but are usually performed only in women with a history of previous embryonic abruption or recurrent miscarriage. Positive anticardiolipin antibodies can still pose a risk to a normal pregnancy. Positive anticardiolipin antibodies affect the endothelial cells of the placental blood vessels, which can lead to placental thrombosis, affecting the blood and oxygen supply to the placenta, leading to abnormal fetal development and even embryonic abruption.