Background Essential thrombocythemia (ET) is a chronic myeloproliferative neoplasm characterized by persistently elevated platelet count without a clear secondary cause. Although most patients with ET are between 55 and 60 years of age, it has been estimated that 20% of women with ET are diagnosed during reproductive ages. Miscarriage is the most frequent complication of ET that has been hypothesized to be caused by microcirculatory disturbances and placental microinfarction. Furthermore, pregnant patients with ET are at increased risk of other pregnancy complications such as preterm delivery and intrauterine growth restriction. Methods This study was planned to evaluate pregnancy outcomes and predictors of obstetric complications in pregnant women with essential thrombocythemia (ET). The data of 21 patients with ET were analyzed retrospectively between 2016 and 2020. Age, parity, history of miscarriage, presence of Janus kinase 2 (JAK2) mutation, history of thrombotic events, treatment of thrombocytosis during pregnancy, and obstetrical outcomes including miscarriage were compared. Results Patients with ET had a significantly higher rate of history of two or more previous miscarriages. Miscarriage and obstetric complications in pregnant women with ET were found to be significantly higher than in the control group. Patients with ET with obstetric complications or miscarriage more frequently had a platelet count of >1000 × 103/μL. Acetylsalicylic acid (ASA) prevented miscarriages, but not obstetric complications, in patients with ET. Conclusion ET increases miscarriage and obstetric complications in pregnancy. Treatment with ASA may reduce pregnancy losses, but not obstetric complications.
