Antiphospholipid Antibody Syndrome Primary

The purpose of the study is to evaluate the ability of placental angiogenesis markers to predict the risk of PE in pregnancy in women with primary APS. To construct reference intervals of placental angiogenesis markers specific to women affected by primary APS in pregnancy by measuring the levels of sFlt-1and PlGF in serum maternal serum and their sFlt-1/PlGF ratio during the trimesters of gestation (I TM, II TM and III TM). For this aim the study will involve recruiting two groups of subjects, one will be cases and one will be controls.