OBJECTIVE: To evaluate complications associated with early postpartum therapeutic anticoagulation. METHODS: A multicenter retrospective cohort study was done to evaluate the association between therapeutic anticoagulation postpartum and major complications (hemorrhagic and wound complications). Secondary outcomes included minor complications, risk factors associated with total complications (including the time to therapeutic anticoagulation resumption after delivery) and recurrent thrombotic events within 6 weeks postpartum. RESULTS: From 2003 to 2015, 232 consecutive women were treated with therapeutic anticoagulation within 96 hours postpartum; among those treated, 91 received unfractionated heparin, 138 received low-molecular-weight heparin, and three received other anticoagulants. The primary outcome, a composite of major hemorrhagic complications (requiring transfusion, hospitalization, volume resuscitation, transfer to intensive care unit, or surgery) and major wound complications, occurred in 7 of 83 (8.4%) for cesarean deliveries and 9 of 149 (6.0%) for vaginal deliveries (P=.490). Total complications (including major and minor hemorrhagic and wound complications) occurred in 13 of 83 (15.7%) for cesarean deliveries compared with 9 of 149 (6.0%) for vaginal deliveries (P=.016). When comparing cases associated with and without complications, the median delay before resuming anticoagulation was significantly shorter for both cesarean (12 vs 33 hours, P=.033) and vaginal deliveries (6 vs 19 hours, P=.006). For vaginal deliveries, 8 of 51 (15.7%) women had complications when anticoagulation was started before 9.25 hours postpartum, compared with 1 of 98 (1.0%) when started after 9.25 hours. For cesarean deliveries, 7 of 21 (33.3%) of women experienced complications compared with 6 of 62 (9.7%) if anticoagulation was started before or after 15.1 hours, respectively. Two (0.9%) episodes of venous thromboembolism occurred within 6 weeks postpartum. CONCLUSION: Among postpartum women who received early therapeutic anticoagulation, major complications occurred in 8.4% for cesarean deliveries and 6.0% for vaginal deliveries. Complications were associated with earlier resumption of therapeutic anticoagulation, particularly before 9.25 hours for vaginal deliveries and before 15.1 hours for cesarean deliveries.