Onset of labor and use of analgesia in women using thromboprophylaxis with 2 doses of low-molecular-weight heparin: insights from the Highlow study

Abstract

BackgroundPeripartum management of women using low-molecular-weight heparin (LMWH) varies widely. Minimum time intervals are required between LMWH injection and neuraxial procedure, and they differ by dose. ObjectivesThe objective of this study was to describe the onset of labor and use of analgesia in women using LMWH and to compare practices between intermediate-dose and low-dose LMWH. MethodsIn the Highlow study (NCT 01828697), 1110 women were randomized to intermediate-dose or low-dose LMWH and were instructed to discontinue LMWH when labor commenced unplanned or 24 hours prior to planned delivery. The required time interval since last injection to receive a neuraxial procedure was ≥24 hours for intermediate-dose LMWH or ≥12 hours for low-dose LMWH. ResultsIn total, 1018 women had an ongoing pregnancy for ≥24 weeks. Onset of labor was spontaneous in 198 of 509 (39%) women on intermediate-dose LMWH and in 246 of 509 (49%) on low-dose LMWH. With unplanned onset, a neuraxial procedure was performed in 37% on intermediate-dose and in 48% on low-dose LMWH (risk difference −11%, 95% CI −20% to −2%). Based on time interval, 61% on intermediate-dose and 82% on low-dose LMWH were eligible for a neuraxial procedure. With planned onset, 68% on intermediate-dose and 66% on low-dose LMWH received a neuraxial procedure, whereas 81% and 93%, respectively, were eligible for a neuraxial procedure (risk difference −13%, 95% CI −18% to −8%). ConclusionWith spontaneous onset of labor, neuraxial procedures were performed less often in women using intermediate-dose LMWH. Irrespective of onset, fewer women on intermediate-dose LMWH than those on low-dose LMWH were eligible for neuraxial procedures based on required time intervals since the last LMWH injection.