Evaluating Clinical Outcomes Related to the Administration of Low-Molecular-Weight Heparin and Unfractionated Heparin in Pregnant Patients Prior to Delivery

The rising use of anticoagulation in pregnancy highlights the need for consistent guidelines regarding the timing of its administration and prevalence of complications. This study aims to evaluate whether the conversion of patients from low-molecular-weight heparin (LMWH) to unfractionated heparin (UFH) at approximately 36 weeks of gestation results in improved outcomes and harm reduction. A retrospective chart review was conducted using data from 141 deliveries of patients who were on LMWH or UFH during their pregnancy up until delivery and delivered at a university-affiliated hospital between January 2015 and September 2022. Outcomes include the prevalence of hemorrhage-associated morbidity and neuraxial anesthesia complications in patients who were switched from LMWH to UFH prior to delivery. Out of 141 deliveries, patients in 38 of the deliveries were converted from LMWH to UFH prior to delivery. The conversion and non-conversion groups had comparable rates of postpartum hemorrhage during delivery (5.3% vs 14.6%, respectively, aOR = 0.42, 95% CI 0.09–2.05, p = 0.29). Conversion and non-conversion groups have no difference in estimated blood loss (406.7 ± 53.0 vs 562.6 ± 73.1 mL, p = 0.98) or quantitative blood loss (655.9 ± 296.6 vs 667.4 ± 62.3 mL, p = 0.89). Our findings demonstrate that there is not a significant difference in postpartum hemorrhage in patients who were switched from LMWH to UFH and the prevalence of neuraxial anesthesia complications was not high enough to be comparable.