Real World Data on Obstetric (OC) and Maternal Complications (MC) Occurring in a Cohort of Patients with Ph Negative Myeloproliferative Neoplasms (MPN): Argentinian Multicentric Study

Introduction: Up to 20% of patients (pts) with essential thrombocythemia (ET) and up to 10-15% of pts with polycythemia vera (PV) are diagnosed before the age of 40 years and the percentage is even lower in pts with primary myelofibrosis (PMF). Pregnancy (Pcy) in MPN is associated with an increased incidence of thrombotic and bleeding events and obstetric complications with live birth rates of 50% to 70%. There are no evidence-based guidelines for the management of these pts and most of the data come from case series of few pts. There are no validated variables that can predict outcomes in pregnant women with MPN.

Objetives:

Primary: To learn the incidence of thromboembolic, hemorrhagic and OC in pregnant women with MPN in Argentina.

Secondary: To evaluate parameters such as mutational status, platelet count, history of complications in previous Pcy, use of aspirin (ASA), low molecular weight heparin (LMWH) or interferon (IFN) and their relationship with obstetric outcomes.

Materials and methods: Retrospective evaluation of medical records of pts with diagnosis of MPN and Pcy. Quantitative variables were expressed as median and interquartile range (IQR) and qualitative variables as total number and percentage (%). Fisher's exact test was used to analyze variables and their association with events and Wilcoxon test for platelet counts.

Results: A total of 30 Pcy in 23 women with a diagnosis of MPN were recorded, 20 Pcy in pts with ET, 4 Pcy in pts with PV and 6 MF pregnancies. Pcy was planned in 56.6% of cases. There were OC in 15/19 previous Pcy. The median age was 32.9 years (IC25-75% 30-36 years). Mutational status was assessed in 22 pts: 9/22 JAK2 +, 7/22 CALR +, 1/22 triple-negative, 1/22 JAK2-CALR- and MPL not performed, 6/22 JAK2- CALR and MPL without data. The overall number of live births and first trimester spontaneous abortions (SA) were 26(86%) and 4(13.3%) respectively, without cases of second (2T) and third trimester (3T) fetal loss or stillbirths. There was a case of neonatal death in a patient with MF. We detected 13 obstetric events (ET: 9/20, PV: 2/4, and MF 2/6): 4 SA, 5 cases of fetal growth retardation, 1 partial placental abruption and 3 placental hematomas. There was no significant association between JAK2 mutational state, history of complications in previous Pcy, platelet count, use of ASA, LMWH or IFN and obstetric outcomes. Two of the pts who had SA presented smoking as a cardiovascular risk factor. There was heterogeneity among hematologist regarding therapeutic management: ASA was indicated in 24 Pcy and LMWH in prophylactic doses during Pcy in 15. In 21/25 cases LMWH was indicated as postpartum prophylaxis, only in 3/21 it was extended for 6 weeks(wks). Before Pcy 17 cases received cytoreductive treatment: 2 with HU and 1 with anagrelide that were discontinued at the time Pcy was confirmed, 5 with peg IFN, and 9 conventional IFN. During Pcy 8 continued with cytoreductive treatment (6/9 conventional IFN, 2/9, pegIFN, including 1 patient previously receiving HU) and 5 initiated IFN (1/5 conventional, 4/5 pegIFN). Platelet counts in pts who did not require cytoreduction dropped from 600 x 10⁹/L (290-1596 x 10⁹/L) at the beginning of Pcy to 470 (240-1548) x 10⁹/L, p=0.0068, and 423 (240-843) x 10⁹/L, p=0.0005, in the 2T and 3T, respectively, with non-significant increase after delivery to 494 x 10⁹/L (122-1600 x 10⁹/L). No cases of maternal thrombosis and 2 episodes of major postpartum bleeding who required surgical intervention one of them with hysterectomy were found.The median time of delivery was at 38 wks of gestation (IC25-75% 36.5-38.5). Vaginal delivery was performed in 6 Pcy, caesarean section (CS) was required due to emergency in 2, because of lack of fetal progression in 2, and 16 were scheduled CS. The median birth weight was 2900g (IC25-75% 2500-3300g). No congenital malformations in live births were detected.

Conclusions: Pcy is a rare but high-risk event in MPN pts with 11/30 OC in this cohort. The live birth rate was high compared to the literature. The risk of MC was low, without thrombotic complications and 2/30 episodes of major postpartum bleeding. There was no correlation between mutational status, platelet count or treatments received and obstetric outcomes. There was a significant reduction in the number of platelets in pts with thrombocytosis without requiring cytoreduction. The high percentage of pts who finished their pregnancy with scheduled CS is highlighted.