Risk Assessment of Critical Obstetric Bleeding With Low-Molecular-Weight Heparin

Background: Use of unfractionated heparin (UFH) during the peripartum period is considered to be a higher risk of critical obstetric bleeding compared to low -molecular -weight heparin (LMWH). However, the evidence for the safety of using LMWH during the peripartum period is currently lacking. Methods: This study retrospectively investigated a nationwide medical database to clarify the safety of using LMWH during childbirth. The Japanese Nationwide Diagnosis Procedure Combination database was retrospectively reviewed, and data from women with childbirth between 2018 and 2022 were collected. Results: Among the overall 354,299 women with childbirth, 3,099 were with obstetric disseminated intravascular coagulation (DIC), 484 were with critical obstetric bleeding requiring massive red blood cell (RBC) transfusion >= 4,000 cc, and 38 were with maternal death. Among the overall women, each of the anticoagulants other than LMWH was associated with critical obstetrical bleeding with an adjusted odds ratio (aOR) greater than 1.0, while LMWH was not associated with critical obstetrical bleeding (aOR, 0.54 (95% confidence interval, 0.11-2.71)). This finding did not change in subgroup analyses among those with Cesarean section. Furthermore, UFH was associated with critical bleeding among the 3,099 women with obstetrical DIC (aOR, 3.91 (2.83-5.46)), while LMWH was not (aOR, 0.26 (0.03-1.37)). Conclusion: The use of UFH was significantly associated with an increased critical obstetric hemorrhage requiring massive RBC transfusion or total hysterectomy. Meanwhile, the use of LMWH was not associated with increased critical obstetric bleeding. LMWH would be safer than UFH to be used for women during childbirth.