Exploratory Aim: To investigate whether duration of anticoagulation (over the range of 3 months to indefinite duration, as determined clinically in routine care) on influences the risks of symptomatic recurrent VTE and clinically-relevant bleeding among children with first-episode, provoked, acute venous thrombosis in whom persistent antiphospholipid antibody positivity is evident at 6 and 12 weeks post-diagnosis.