Duration of labor among women with thromboembolic events: A Swedish register study

Abstract

Duration of labor among women with thromboembolic events: A Swedish register study Susanne Hesselmana,b,*, Anna Wikmana, Roxanne Hastiea,c, Anna-Karin Wikströma, Lina Bergmana,d,e,1, Anna Sandströma,f,1 a Department of Women’s and Children’s Health, Uppsala University, Uppsala, Sweden b Center for Clinical Research, Uppsala University, Falun, Sweden c Mercy Perinatal, Mercy Hospital for Women, Melbourne, Australia d Department of Obstetrics and Gynecology, Stellenbosch University, Cape Town, South Africa e Department of Obstetrics and Gynecology, Institute of Clinical Science, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden f Clinical Epidemiology Division, Department of Medicine Solna, Karolinska Institute, Stockholm, Sweden A R T I C L E I N F O Article history: Received 29 April 2021 Received in revised form 15 June 2021 Accepted 19 July 2021 Available online 22 July 2021 Keywords: Delivery Epidural analgesia Heparin Pregnancy Venous thromboembolism A B S T R A C T Introduction: Inflammation is central to initiation of labor and coagulation is closely interlinked with inflammation. Low-molecular-weight-heparin (LMWH) promotes inflammatory cervical remodeling, myometrium contractility and has been associated with shorter duration of labor. Material and methods: This was a cohort study of 136,661 deliveries 2013–2017, identified in the Swedish Pregnancy Register with prospectively collected pregnancy and labor characteristics. Information of duration of labor was retrieved from the electronic birth records and analyzed with Cox proportional hazard regressions according to previous or current thromboembolic disease (overall) with or without LMWH treatment with non-exposed as reference. Results: The crude hazard ratio for vaginal delivery was not different between women with thromboembolic disease and women without thromboembolic disease (HR 0.99, 95 % CI 0.91–1.09). A lower hazard ratio for vaginal delivery was observed among women with venous thromboembolism (VTE) with concomitant LMWH use/treatment (adjusted HR 0.86, 95 % CI 0.76 0.98) compared to nonexposed, implying a longer duration of labor in these cases. Conclusion: Thromboembolic disease was not associated with shorter duration of labor and in presence of LMWH these women experienced longer duration of labor.