Objective: To compare bleeding complications in pregnant patients treated with low-molecular-weight heparin (LMWH) to untreated controls.Study design: A case-control study of patients from 2001 to 2005 who received prophylactic or therapeutic doses of LMWH during pregnancy was carried out. Indications for LMWH included current or prior thromboembolism, thrombophilia, or heart valve replacement. Controls were chosen in a 2:1 ratio to cases, matched for delivery route, and selected as the next two consecutive deliveries. The primary outcome was postpartum hemorrhage (PPH). Odds ratios (ORs) were calculated with 95% confidence intervals (CIs).Results: Forty-nine women treated with LMWH delivered 55 infants. Current or prior thromboembolic disease was the anticoagulation indication in 15/55 (27.3%) and 26/55 (47%) of pregnancies, respectively. There were more obese gravidas (OR 3.91, CI 1.70 to 9.09) and labor induction was more common in the LMWH group, 25/55 (45%) vs 29/110 (26%), P ¼ 0.01. There was no difference in estimated blood loss (295.7±145.7 vs 308.6±111.9 cm 3 , P ¼ 0.62 vaginal; 687.5±251.8 vs 765.0±313.2 cm 3 , P ¼ 0.34 cesarean), PPH (6/55, 11% vs 9/110, 8.2%; OR 1.37, CI 0.16 to 11.5) or transfusion (3/55, 5.4% vs 4/110, 3.6%; OR 1.50, CI 0.3 to 7.48) between the cases and controls. There were two cases of postpartum pulmonary emboli, one with a maternal mortality.Conclusion: Bleeding complications, including PPH and transfusion, in patients treated with LMWH during pregnancy were not increased when compared to normal controls matched for delivery route.

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