Abstract 216: Risk of Thrombosis Remains Elevated for 12 Weeks After Labor and Delivery
Background: The risk of arterial and venous thrombosis remains elevated during the conventionally defined 6-week postpartum period, but it is unknown whether heightened risk persists beyond this point. Given the magnitude of postpartum thrombotic risk, we hypothesized that it remains elevated beyond 6 weeks after labor and delivery.
Methods: Using administrative claims data from all nonfederal acute care EDs and hospitals in California, we compared the risk of thrombotic events during sequential 6-week periods after delivery. We used validated ICD-9-CM codes to identify women hospitalized for ischemic stroke, acute MI, PE, or DVT; in a sensitivity analysis we included a broader list of thrombosis codes, including cerebral sinus thrombosis. We compared each patient’s likelihood of labor and delivery in the 0-to-6 week period before a thrombotic event (case period) versus a 6-week period exactly 1 year prior (control period). We repeated this case-crossover analysis for the 6-to-12 week, 12-to-18 week, and 18-to-24 week periods before the thrombotic event. Odds ratios for each time period were calculated with conditional logistic regression because each patient was matched to her own control period.
Results: Of 648,148 women with a first documented thrombotic event between 2007 and 2011, 1,620 had delivered during the prior 24 weeks. Their mean age was 30 (±7) years; 16% were black and 35% Hispanic. The risk of thrombosis was markedly higher in the 0-to-6 week period after delivery (OR, 6.6; 95% CI, 5.1-8.4) versus 1 year prior. Notably, thrombotic risk remained elevated during the 6-to-12 week period after delivery (OR, 2.3; 95% CI, 1.8-3.1). The risk then essentially normalized in the 12-to-18 week period (OR, 1.2; 95% CI, 0.9-1.6) and fully resolved in the 18-to-24 week period (OR, 0.9; 95% CI, 0.7-1.2). This pattern was similar in our sensitivity analysis and when we assessed the specific endpoints of stroke, acute MI, and PE or DVT.
Conclusions: The risk of thrombosis remains elevated beyond the traditional 6-week postpartum period, and persists for at least 12 weeks after delivery. This should be considered when evaluating postpartum women with symptoms of possible thrombosis, or making recommendations about postpartum thrombosis prophylaxis or treatment.
Author Disclosures: H. Kamel: None. B.B. Navi: None. N. Sriram: None. D.A. Hovsepian: None. M.S.V. Elkind: None.
This research has received full or partial funding support from the American Heart Association, National Center.
- © 2014 by American Heart Association, Inc.