Gestational Platelet Trends and Outcomes in Women with Myeloproliferative Disorders Characterized by Thrombocytosis

Abstract Myeloproliferative disorders (MPD), including essential thrombocythemia (ET) and polycythemia vera (PV) are most commonly diagnosed after the sixth decade, but as many as 20 percent of patients are younger than 40 years of age. This introduces the issue of disease management during gestation. Pregnant women with ET are reported to have an increased risk of pregnancy complications, with a successful live birth rate of 50 to 57 percent and a first trimester miscarriage rate of 26 to 36 percent (Harrison 2005). This is compared to an anticipated first trimester loss of 15 to 20 percent for women without ET (Hatasaka 1994). Late pregnancy loss has been reported to occur in 5 to 9.6 percent of ET pregnancies, compared to 0.5 percent of normal pregnancies (Cook 1995, Martinelli 2000). In this retrospective case series review, however, examination of 8 women with MPD (6 with ET; 2 with PV and thrombocytosis; 6 with the JAK2 mutation) and their combined 12 pregnancies reveals a 100 percent live birth rate with no disease related complications. Maternal age ranged from 27 to 41 years with gestational ages averaging 39.1 weeks (ranging from 36.9 to 41.3 weeks). There were no thrombotic or significant bleeding events observed. The majority of women were treated with only aspirin 325mg daily throughout gestation, with the 2 women with PV also receiving gestational enoxaparin 60mg daily that was continued for 6 weeks post-partum. Platelet counts decreased throughout gestation in all pregnancies, reaching a nadir at delivery before rebounding to pre-gestational range within 1 to 2 months post-partum. On average, the platelet count decreased by 53.1 percent during gestation (ranging from 28.4 to 70.9 percent). Forty-two percent of pregnancies demonstrated a normal platelet count at the time of delivery. The significant decline in platelet counts throughout gestation may be protective against thrombosis. This decrease is unlikely to represent hemodilution of pregnancy alone as platelet counts continued to decline until delivery, whereas rapid maternal plasma volume expansion occurs between weeks 9 and 34 of gestation, followed by only a modest increase in plasma volume thereafter. Moreover, benign gestational thrombocytopenia occurs in only 5 percent of normal pregnancies. In summary, use of aspirin or enoxaparin in this series did not result in any bleeding complications. The data from this cohort suggests that a diagnosis of ET or PV does not lead to increased pregnancy complications or loss. Platelets Trends Case Platelet Count on Day of Delivery Average Non-Gestational Platelet Count Highest Recorded Platelet Count % Platelet Reduction** 1 436,000 756,500 855,000 42.4 2 331,000 840,000 1,168,000 60.6 3 220,000 757,000 757,000 70.9 4a 581,000 1,481,000 2,006,000 60.8 4b* 1,025,000 1,431,000 1,493,000 28.4 5a 389,000 1,038,000 1,236,000 62.5 5b 396,000 977,000 1,089,000 59.5 5c 552,000 1,145,000 1,145,000 54.4 6 Unknown 842,000 892,000 7 649,000 1,185,000 1,421,000 45.2 8a 702,000 1,298,000 1,398,000 45.9 8b 606,000 1,302,000 1,445,000 53.5 *Twin delivery **Between average non-gestational platelet count and delivery date platelet count Download : Download high-res image (139KB) Download : Download full-size image