Inherited thrombophilic conditions are associated with adverse pregnancy outcomes, including severe pre-eclampsia, fetal loss, abruptio placentae, and IUGR. Although the prevalence of these complications is approximately 8% in the general population, the presence of thrombophilic conditions is associated with a significantly increased recurrence risk. Thrombophilic conditions most strongly associated with APO include FVL, PGM, and deficiencies of PS, PC, and antithrombin. However, other thrombophilic conditions, such as protein Z deficiency, appear to be associated with an increased risk of pregnancy complications. Antenatal administration of heparin to prevent pregnancy complications has shown promise in small studies, but an adequate randomized, placebo-controlled trial is necessary to determine whether heparin administration is beneficial in preventing APO, with a favorable safety profile.