Treatment with aspirin or interferon may be associated with higher odds of live birth in pregnant patients with myeloproliferative neoplasms (MPNs), according to results of a systematic review and meta-analysis published in JAMA Network Open.

Given that different MPNs have similar thrombotic and hemorrhagic complications, the investigators aimed to evaluate the associations between the use of aspirin, heparin, interferon, or combinations of those agents with live birth rate and adverse maternal outcomes (arterial or venous thrombosis, hemorrhage, and preeclampsia) in pregnant patients with MPNs.

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Systematic searches were conducted in MEDLINE, Embase, Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials, and the MEDLINE Epub Ahead of Print and In-Process and Other Non-Indexed Citations. Key search terms were: “myeloproliferative disorders,” “polycythemia vera,” “essential thrombocythemia,” and “primary myelofibrosis.”

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Ultimately, 22 studies comprising data on 1210 pregnancies were included. Fifteen studies reported on patients with essential thrombocythemia. The remaining studies reported on polycythemia vera (3 studies) or any classical MPN (4 studies); no studies including patients exclusively with myelofibrosis met the inclusion criteria, nor were any studies randomized clinical trials.

Live birth rate was reported in all studies; overall, the live birth rate was 71.3% (95% CI, 65.1%-77.6%). Higher odds of live birth were associated with the use of aspirin (unadjusted odds ratio [OR], 8.6; 95% CI, 4.0-18.1) and the use of interferon with or without aspirin or heparin (unadjusted OR, 9.7; 95% CI, 2.3-41.0). The addition of heparin to aspirin was not associated with higher odds of live birth (unadjusted OR, 2.1; 95% CI, 0.5-9.0) compared with aspirin alone.

In total, 16 of the 22 studies, including 743 pregnancies, reported the rates of any adverse events; the pooled rate of any adverse event was 9.6% (95% CI, 5.9%-13.3%). The most common adverse event was preeclampsia, which had an incidence of 3.1% (95% CI, 1.7%-4.5%).

Most of the studies were retrospective and focused on essential thrombocythemia, and early pregnancy losses may have been underreported, leading to ascertainment bias.

The researchers concluded that “the prevalence of MPNs in pregnancy appears to be increasing; consequently, there may be an increased need to optimize management of these pregnancies.”


1.      Maze D, Kazi S, Gupta V, et al. Association of treatments for myeloproliferative neoplasms during pregnancy with birth rates and maternal outcomes [published online October 4, 2019]. JAMA Netw Open. doi:10.1001/jamanetworkopen.2019.12666