American Journal of Hematology 28:66 (1988) Letter to the Editor: Essential Thrombocythemia and Pregnancy We have read with interest the brief report of Falconer et al [I] on recurrent abortions and fetal growth retardation associated with essential thrombocytemia (ET) Several reports of pregnancy associated with ET have been published, and there have been considerable variations regarding frequency of obstetric complications Hoagland and Silverstein [2] did not encounter obstetric complications in seven female patients younger than 30 years, with normal pregnancies and deliveries of normal infants in two patients However, Bellucci et al [3] found spontaneous abortions, premature delivery, and abruptio placentae in of 22 patients similar in age of procreation We have seen four women, aged less than 40, diagnosed as having ET, according to the Polycythemia Vera Study Group (PVSG) criteria [4].They had no previous history of abortions, and two of them experienced normal pregnancies and deliveries after diagnosis The first patient, a 24-year-old woman, became pregnant after diagnosis of ET Gestation was normal until the 37th week, when she suffered from mild toxemia Delivery was induced on the 38th week, and the male neonate weighed 3,230 g The Apgar score was There were no hemorrhagic complications during delivery The second patient, a 25year-old woman, had an uncomplicated pregnancy thirty months after disgnosis of ET Delivery occurred during the 38th week without complications, and the female newborn weighed 2,300 g The Apgar score was Both patients have remained asymptomatic at 67 and 54 months after diagnosis, with a platelet count slightly less than since *,Oo0 109'L No treatment has been diagnosis Falconer et al [ 11 report two cases of ET with obstetric complications, but the-diagnostic criteria for ET are not specified In fact, case had a normal platelet count before splenectomy, which is known to produce reactive thrombocytosis, a criterion for exclusion of ET Falconer et al suggest that the use of antiaggregating agents in preventing fetal losses in ET However, to our knowledge, there are no conclusive studies supporting the usefulness of antiaggregating drugs in ET Moreover, in a recent randomized trial from PVSG [5], aspirin and dipyridamole did not prevent thrombotic complications in 1988 Alan R Liss, Inc patients with polycythemia Vera, another myeloproliferative disease, commonly present along with thrombocytosis and thrombotic complications Indeed, their use was associated with a significant increase incidence of severe gastrointestinal hemorrhage At present, there are no data available which prove that obstetric complications in ET might be reduced by the use of platelet antiaggregating agents On the other hand, the theoretical basis for using these agents is unclear because, it is still unknown whether hemorrhages or thromboses are implicated in the pathogenesis of obstetric complications in ET Mariano Linares, MD Emilio Pastor, MD lsidro Jarque, MD Guillermo Sanz, MD Miguel Sanz, MD Department of Clinical Hematology Hematology Service, Hospital La Fe 46009 Valencia, Spain REFERENCES Falconer J, Pineo G, Blahey W, Bowen T, Docksteader B, Jadusingh I: Essential thrombocythemia associated with recurrent abortions and fetal growth retardation Am J Hematol 25:345, 1987 Hoagland HC, Silverstein MN: Primary thrombocythernia in young patient Mayo Clin Proc 53:578, 1978 Bellucci S, Janvier M, Tobelem G, Flandrin G, Charpak Y, Berger R, Boinou, M: Essential thrombocythemias Clinical evolutionary and biological data Cancer 58:2440, 1986 Murphy S, Iland H, Rosenthal D, Laszlo J: Essential thrombocythemia: An interim report from the Polycythemia Vera Study Group Seminars in Hematology 23: 177, 1986 Tartaglia AP, Goldberg JD, Berk PD, Wasserman LR: Adverse effects of antiaggregating platelet therapy in the treatment of polycythemia Vera Semin Hematol23: 172, 1986