Obstetric and neonatal outcomes in pregnant women treated with high-dose thromboprophylaxis: a retrospective, single-center study

Introduction: It is well established that women with very high risk of developing antenatal thrombosis benefit from high-dose thromboprophylaxis, however data on outcomes and the safety and efficacy of thromboprophylaxis are scarce. The aim of the study was to evaluate the safety and effectiveness of the Swedish guidelines for high-dose thromboprophylaxis and the obstetric outcomes in a single-center patient cohort. Patients and methods: Forty-seven women treated at the Department of Obstetrics and Gynecology, Karolinska University Hospital, Solna, Sweden, between 2004 and 2017 were included in this retrospective study. Data on treatment, obstetric, and neonatal outcomes and medical history were collected. Data derived from the Swedish Medical Birth Registry on women giving birth in Stockholm County 2004-2016 were used as controls. The protocol of the study was approved by the Regional Ethics Committee in Stockholm, Sweden. Results: The initial thromboprophylaxis dose was 5000 IU dalteparin twice daily. No patient developed ablatio placentae or preeclampsia. One patient suffered antenatal muscle vein thrombosis. Six patients (12.7%) suffered postpartum hemorrhage (PPH); however only one patient had severe PPH. Forty-eight children were born. Three children (6%) were diagnosed with intrauterine growth retardation, five (10%) were born small for gestational age and seven (15%) were born premature, the majority of which (except for two premature) to women with thrombophilia. Discussion: High-dose thromboprophylaxis was effective and safe. The incidence of preeclampsia and ablatio was lower than in controls; however, neonatal outcomes were worse, especially among mothers with thrombophilia. Due to the diversity of the thrombophilic traits, no thrombophilia-specific conclusion could be drawn. Stricter adherence to the guidelines could further decrease the risk for bleeding, whereas more frequent antenatal controls could possible improve neonatal outcomes.