Myeloproliferative Disorders in Pregnancy




This article reviews pregnancy outcome in women diagnosed with a myeloproliferative neoplasm (MPN), and discusses possible risk markers and the pathogenesis of poor pregnancy outcome. An outline of the key factors regarding the diagnosis and management of MPN in women of reproductive potential is followed by a description of the authors’ management strategy for standard and high-risk pregnancy in MPN patients.


The myeloproliferative neoplasms (MPNs), previously known as the myeloproliferative disorders, are generally indolent stem cell malignancies, characterized by a propensity to thrombotic or hemorrhagic events and, less frequently, transformation to myelofibrosis or acute myeloid leukemia. The MPNs defined by the World Health Organization (WHO) encompass the more commonly encountered essential thrombocythemia (ET), polycythemia vera (PV), and primary myelofibrosis (PMF), and the rarer entities MPN unclassified, MPN syndromes overlapping with myelodysplasia, mast cell disorders, chronic neutrophilic leukemia, and hypereosinophilic syndrome. The combined incidence of ET, PV, and PMF is approximately 6 in 100,000 to 9 in 100,000, with a peak frequency between 50 and 70 years. However, for ET in particular there is a second peak in women of reproductive age, and 15% of patients with PV are younger than 40 years at the time of diagnosis. Thus these diseases are encountered in women of reproductive potential, and may indeed be diagnosed in pregnancy or during investigation of recurrent pregnancy loss or infertility. Historical case reports of pregnancy and retrospective case series, albeit likely to be subject to reporting bias, suggest significant maternal morbidity and poor fetal outcome. Pregnancy in these conditions is clearly complicated, and a proportion of women with MPN will require disease-specific intervention in pregnancy.


Pathogenesis of MPN


MPNs result from the transformation of a hemopoietic progenitor cell, characterized by overproduction of mature blood cells. In 2005, 4 groups simultaneously reported the discovery of a point mutation in exon 14 of Janus Kinase 2 (JAK2V617F), where phenylalanine is substituted by valine, which enables constitutive activation of JAK 2. Both wild-type and mutant JAK2 bind to the intracytoplasmic tail of many common hemopoietic cytokine receptors, which include those cognate receptors for erythropoietin, thrombopoietin (TPO), and granulocyte colony stimulating factor. When the ligand binds to one of these receptors, phosphorylation of JAK2 and the receptor itself occurs, initiating signaling via the JAK-STAT, MAPK, and PI3K pathways. This process is independent of the presence of ligand receptor interaction in the presence of JAK2V617F ( Fig. 1 ). The JAK2V617F mutation is present in 95% of patients with PV and 50% of patients with ET or myelofibrosis. Many of the remaining patients with JAK2V617F-negative PV have a mutation in exon 12. A proportion of patients with ET or myelofibrosis have one of several mutations of the transmembrane domain of the TPO receptor cMPL, which also causes constitutive activation. All these mutations have been shown to produce an MPN-like phenotype in murine models.




Fig. 1


The role of JAK2 in the signalling pathway and the erythropoietin receptor. In the absence of erythropoietin, the erythropoietin receptor binds JAK2 as an inactive dimer ( A ). The binding of erythropoietin induces conformational change in the erythropoietin receptor and phosphorylation of JAK2 and the cytoplasmic tail of the receptor ( B ) leading to signalling through the Janus kinases and signal transducers and activators of transcription (JAK-STAT), phosphatidylinositol 3 kinase (PI3K) and RAS and mitogen activated protein kinase (RAS-MAPK). In cells with JAK2 V617F the signalling pathways are constitutively increased even in the absence of erythropoietin ( C ). ( Adapted from Campbell PJ, Green A. The mechanisms of disease. The Myeloproliferative Disorders. The New England Journal of Medicine 2006;355:2452–66.)




Pregnancy outcome data and risk factors for MPN


ET is the commonest MPN in women of childbearing age, and a significant number of cases of pregnancy have been reported in the literature, but these data are insufficient to devise evidence-based management guidelines. A meta-analysis reported the outcome of 461 pregnancies in women diagnosed with ET. The live birth rate was 50% to 70%; first trimester loss occurred in 25% to 40% and late pregnancy losses in 10%. Rates of placental abruption (3.6%) and intrauterine growth restriction (IUGR) (4.5%) were higher than in the general population. Postpartum thrombotic episodes were reported in 5.2% of pregnancies and pre-/postpartum hemorrhage in 5.2%. A summary of 208 historical cases of ET collated from case series that included greater than 6 pregnancies produced comparable data ( Table 1 ). The literature for pregnancies affected by PV is sparse; pregnancy outcome in the authors’ own case series of 18 pregnancies in PV combined with 20 historical reports was concordant with the pregnancy outcomes in ET, and is summarized in Table 2 . In PV first trimester loss was the most frequent complication (21%), followed by late pregnancy loss (18%), IUGR (15%), and premature delivery (13%), which included 3 neonatal deaths resulting in a 50% survival rate. Maternal morbidity was also significant including 3 thromboses, 1 large postpartum hemorrhage, 4 cases of preeclampsia, and 1 maternal death associated with evidence of a deep vein thrombosis, pulmonary emboli, sagittal sinus thrombosis, and disseminated intravascular coagulation. The literature regarding PMF is more limited. A report of 4 pregnancies in PMF combined with 4 historical cases suggested a 50% risk of fetal loss; no maternal complications of thrombosis or disease progression were noted, but the numbers are probably too small to draw any firm conclusions ( Table 3 ).



Table 1

Summary of the literature regarding ET in pregnancy



































































































































































































Author Ref. Patients, n Pregnancies, n Maternal Outcome Live Birth Total Pregnancy Loss Total Loss <12/40 Loss >12/40 IUGR Placental Abruption Live Birth Premature Delivery <37/40 Live Birth FTD
Belluci et al 3 11 Detail not available 4 7 6 1 Detail not available 1 2 2
Beard et al 6 9 1 phlebitis, 1 leg ulcer, 1 PPH 8 1 1 0 0 0 1 7
Leone et al 8 10 Detail not available 7 3 0 3 Detail not available 0 0 7
Pagliaro et al 9 15 2 VTE, 2 TIA, 1 hemorrhage 9 6 4 including 1 TOP 2 2 0 4 5
Randi et al 13 16 3 VTE 13 3 3 0 0 0 3 10
Cincotta et al 12 30 1 PE 17 13 5 including 1 ectopic 8 2 5 5 12
Bangerter et al 9 17 1 TIA, 2 acquired vWD, 3 vaginal bleeds, 2 epistaxis 11 6 6 0 0 0 3 8
Niittyvuopio et al 16 40 1 eclampsia, 2 PET, 1 vaginal bleed 26 (1 twin) 15 13 2 1 0 2 23
Gangat et al 36 63 1 PET, 2 hematoma, 1 PPH 38 25 22 including 1 ectopic, 1 TOP 3 Detail not available 1 1 37
Melillo et al 92 122 5 DVT, 3 PET, 1 PPH 92 30 23 7 2 1 12 80
Passamonti et al 78 113 5 PET 44 34 Detail not available Detail not available 7 Detail not available Detail not available Detail not available
Palandri et al 13 24 Detail not available 15 9 Detail not available Detail not available 0 1 0 Detail not available
Total 295 470 284/470 152/470 83/333 26/333 14/386 9/357 33/357 191/333
(60%) (32%) (25%) (8%) (4%) (3%) (9%) (57%)

Abbreviations: DVT, deep vein thrombosis; FTD, full-term delivery; IUGR, intrauterine growth restriction; PE, pulmonary embolism; PET, preeclampsia/toxemia; PPH, postpartum hemorrhage; TIA, transient ischemic attack; TOP, termination of pregnancy; VTE, venous thromboembolism; vWD, von Willebrand disease.


Table 2

Summary of the literature regarding PV in pregnancy
























































































































































































Author Ref. Patients, n Pregnancies, n Treatment During Pregnancy High Risk Maternal Outcome Live Births, n Pregnancy Loss, n First Trimester Miscarriage Stillbirth (Gestation) IUGR Placental Abruption Live Birth <37/40 Live Birth FTD
Crowley et al 1 1 Aspirin + dipyridamole No Death 0 1 1 TOP 0 0 0 0 0
Centrone et al 1 3 Nil No Alive 1 2 2 0 0 0 0 1
Ferguson et al 1 2 Nil No Alive, PET 2 0 0 0 0 0 0 2 PET
Ruch and Klein 1 2 None No Alive, PET 1 1 0 1 (35/40) PET 1 0 0 1
Subtil et al 1 3 Aspirin, heparin, venesection No Alive, PE postpartum 1 2 0 2 (24/40 and 28/40) 2 0 1 (32/40) 0
Hochman and Stein 1 4 Nil Yes Alive, PET 2 2 0 2 (5 & 7 months) PET 0 0 1 (7 months, PET), 1 (8 months) 0
Harris and Conrad 2 2 Nil No Alive, PPH 2 0 0 0 0 0 0 2
Ruggeri et al 1 2 Heparin 3/52 postpartum No Alive, PE 24/7 postpartum 1 1 1 0 0 0 0 1
Pata et al 1 1 Hydroxyurea 9/40 then nil No Alive 1 0 0 0 0 0 0 1
Robinson et al 8 18 (1 twin) Varied: venesection, aspirin, interferon LMWH, vitamin C+E No Alive, 1 PET 11 7 4 2 3 0 1 (34/40, IUGR), 1 (36/40), 1 (26/40) (NND) 9
Total 18 38 1 yes 1 death, 4 PET, 2 PE, 1 PPH 22, 3 neonatal deaths 16 8 7 6 0 6 17

Abbreviations: LMWH, low molecular weight heparin; NND, neonatal death.

Data from Robinson S, Bewley S, Hunt BJ, et al. The management and outcome of 18 pregnancies in women with polycythemia vera. Haematologica 2005;90:1477–83.


Table 3

Summary of the literature regarding PMF in pregnancy





















































































































Author Ref. Patients, n Pregnancy, n Treatment Prepregnancy Treatment During Pregnancy Maternal Outcome First Trimester Miscarriage Stillbirth (Gestation) IUGR Placental Abruption Live Birth Premature Delivery <37 wk
Taylor et al 1 1 Supportive Supportive No complications 0 0 0 0 1 elective induction at 36 wk
Gotic et al 1 1 None None No complications 0 30 (placental infarctions) 0 0 0
2 None None No complications 0 27 (placental infarctions) 0 0 0
3 Interferon-α Interferon-α No complications 0 0 1 0 1 elective delivery at 34 wk due to IUGR, birth weight 2000 g
Tulpule A 3 (2 preceding diagnosis PMF) Aspirin Aspirin Disseminated TB 0 0 0 0 1 FTND
B 1 Aspirin Aspirin, LMWH Postpartum hemorrhage 0 0 0 0 1 FTND
B 2 Aspirin Aspirin, LMWH No complications 0 24/40 cardiac malformation 0 0 0
B 3 Aspirin Aspirin, LMWH No complications 1 0 0 0 0
Total 4 8 3 3 0 3 1 0 4

Abbreviation: FTND, full-term normal delivery.

Data from Tulpule S, Bewley S, Robinson SE, et al. The management and outcome of four pregnancies in women with idiopathic myelofibrosis. Br J Haematol 2008;142:480–2.




Pregnancy outcome data and risk factors for MPN


ET is the commonest MPN in women of childbearing age, and a significant number of cases of pregnancy have been reported in the literature, but these data are insufficient to devise evidence-based management guidelines. A meta-analysis reported the outcome of 461 pregnancies in women diagnosed with ET. The live birth rate was 50% to 70%; first trimester loss occurred in 25% to 40% and late pregnancy losses in 10%. Rates of placental abruption (3.6%) and intrauterine growth restriction (IUGR) (4.5%) were higher than in the general population. Postpartum thrombotic episodes were reported in 5.2% of pregnancies and pre-/postpartum hemorrhage in 5.2%. A summary of 208 historical cases of ET collated from case series that included greater than 6 pregnancies produced comparable data ( Table 1 ). The literature for pregnancies affected by PV is sparse; pregnancy outcome in the authors’ own case series of 18 pregnancies in PV combined with 20 historical reports was concordant with the pregnancy outcomes in ET, and is summarized in Table 2 . In PV first trimester loss was the most frequent complication (21%), followed by late pregnancy loss (18%), IUGR (15%), and premature delivery (13%), which included 3 neonatal deaths resulting in a 50% survival rate. Maternal morbidity was also significant including 3 thromboses, 1 large postpartum hemorrhage, 4 cases of preeclampsia, and 1 maternal death associated with evidence of a deep vein thrombosis, pulmonary emboli, sagittal sinus thrombosis, and disseminated intravascular coagulation. The literature regarding PMF is more limited. A report of 4 pregnancies in PMF combined with 4 historical cases suggested a 50% risk of fetal loss; no maternal complications of thrombosis or disease progression were noted, but the numbers are probably too small to draw any firm conclusions ( Table 3 ).



Table 1

Summary of the literature regarding ET in pregnancy



































































































































































































Author Ref. Patients, n Pregnancies, n Maternal Outcome Live Birth Total Pregnancy Loss Total Loss <12/40 Loss >12/40 IUGR Placental Abruption Live Birth Premature Delivery <37/40 Live Birth FTD
Belluci et al 3 11 Detail not available 4 7 6 1 Detail not available 1 2 2
Beard et al 6 9 1 phlebitis, 1 leg ulcer, 1 PPH 8 1 1 0 0 0 1 7
Leone et al 8 10 Detail not available 7 3 0 3 Detail not available 0 0 7
Pagliaro et al 9 15 2 VTE, 2 TIA, 1 hemorrhage 9 6 4 including 1 TOP 2 2 0 4 5
Randi et al 13 16 3 VTE 13 3 3 0 0 0 3 10
Cincotta et al 12 30 1 PE 17 13 5 including 1 ectopic 8 2 5 5 12
Bangerter et al 9 17 1 TIA, 2 acquired vWD, 3 vaginal bleeds, 2 epistaxis 11 6 6 0 0 0 3 8
Niittyvuopio et al 16 40 1 eclampsia, 2 PET, 1 vaginal bleed 26 (1 twin) 15 13 2 1 0 2 23
Gangat et al 36 63 1 PET, 2 hematoma, 1 PPH 38 25 22 including 1 ectopic, 1 TOP 3 Detail not available 1 1 37
Melillo et al 92 122 5 DVT, 3 PET, 1 PPH 92 30 23 7 2 1 12 80
Passamonti et al 78 113 5 PET 44 34 Detail not available Detail not available 7 Detail not available Detail not available Detail not available
Palandri et al 13 24 Detail not available 15 9 Detail not available Detail not available 0 1 0 Detail not available
Total 295 470 284/470 152/470 83/333 26/333 14/386 9/357 33/357 191/333
(60%) (32%) (25%) (8%) (4%) (3%) (9%) (57%)

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Sep 16, 2017 | Posted by in HEMATOLOGY | Comments Off on Myeloproliferative Disorders in Pregnancy

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