Pregnancy and MPN

There is a distinct set of challenges for patients who become pregnant and have a diagnosis of myeloproliferative neoplasms (MPN), as previously discussed on the MPN Hub. These patients have an increased risk of thrombosis and hemorrhage, especially during delivery and postpartum, in addition to consequences for fetal growth, including placental insufficiency, stillbirth, and premature delivery.¹ As a result, complex management strategies are required to ensure the best possible maternal and fetal outcomes. Best practice recommendations for managing pregnant patients with MPN have previously been reported on the MPN Hub. Here, we outline common risks, challenges, and further practice recommendations in the management of this patient population.

Risks and challenges¹

• Pregnancy-induced hypercoagulability presents a specific set of challenges.
  • The risk of venous thromboembolism is increased 4- to 6-fold in these patients.
  • This risk is greatest postpartum due to increased platelet counts and hematocrit levels.
• The risk of overall pregnancy complications is highest during the first trimester.
• As previously covered by the MPN Hub, fetal and maternal complications include maternal thrombosis, hemorrhage, and placental dysfunction
• Treatment options should be discussed with the patient prior to conception, due to some forms of MPN therapy being teratogenic.

Treatment options²

• Aspirin is prescribed to reduce the risk of pre-eclampsia and fetal death.
  • Studies have shown increased live birth rates with aspirin treatment.
• Conversely, treatment with aspirin must be carefully considered if the patient has acquired von Willebrand syndrome, as the condition presents a further increased risk of bleeding.
  • Patient clinical parameters are tested early in pregnancy and during the third trimester.
• Low molecular weight heparin treatment is recommended as prophylaxis against prior thrombotic events.
  • Heparin should only be administered when the risk of venous thromboembolism is >3%, due to net clinical benefit.
  • Heparin should not be administered if the risk is <1%.
• Venesection reduces hematocrit levels to predefined ranges according to each trimester:
  • 0.31–0.41% (first trimester)
  • 0.30–0.38% (second trimester)
  • 0.28–0.39% (third trimester)
• If cytoreduction is imperative, the only recommended treatment is pegylated interferon alfa-2a as there are no current reports of teratogenesis.
  • All other cytoreductive therapies, including hydroxyurea and anagrelide, are unusable in pregnant patients due to teratogenic effects.

Practice recommendations²

• Management strategies used to mitigate risks to mother and fetus are defined according to the stage of pregnancy (Figure 1).

Figure 1. Management strategies according to pregnancy stage in patients with MPN*

LMWH, low molecular weight heparin; MPN, myeloproliferative neoplasms.
*Adapted from Robinson and Harrison.²

 Conclusion

Pregnant patients diagnosed with MPN require multidisciplinary management to ensure the strategies associated with each stage of pregnancy are implemented and optimized. While maternal and fetal outcomes are improving with current therapeutic options and risk-mitigating recommendations, further advancement and refinement of management strategies is warranted.