6574 Background: Pregnancy in women with myeloproliferative neoplasms (MPNs) is associated with increased thrombotic and obstetric risk, yet contemporary real-world data describing maternal and fetal outcomes remain limited. We evaluated pregnancy-related outcomes in women with MPNs and examined potential risk predictors. Methods: We conducted a retrospective cohort study using the TriNetX network, a federated multicenter network of de-identified electronic health records from participating healthcare organizations. Pregnant women with essential thrombocythemia (ET), polycythemia vera (PV), or myelofibrosis (MF) were identified. The primary outcome was all-cause mortality. Secondary outcomes included deep vein thrombosis (DVT), miscarriage, pre-eclampsia, eclampsia, preterm labor, and intrauterine growth restriction (IUGR). Subgroup analyses were performed using propensity score matching for age, race, ethnicity, and comorbidities to compare outcomes by Low Molecular Weight Heparin (LMWH) exposure, race, maternal age, and MPN subtype. Risk ratios (RR) with 95% confidence intervals (CI) were calculated. Results: A total of 1,904 pregnancies were identified (mean age 31.1±7.0 years).The cohort was predominantly non-Hispanic (66.2%) and White (59.1%). ET accounted for 90.3% of cases, followed by PV (8.0%) and MF (1.7%). Overall rates of maternal mortality and DVT were 2.8% and 2.6%, respectively. Adverse obstetric outcomes included miscarriage (9.6%), pre-eclampsia (12.4%), eclampsia (1.3%), preterm labor (9.1%), and IUGR (8.5%). In matched analyses, LMWH use was associated with a numerically lower risk of miscarriage compared with no LMWH (6.8% vs 10.4%; RR 0.66, 95% CI 0.42–1.04), without significant differences in pre-eclampsia, preterm labor, or IUGR. Outcomes were similar between White and African American patients. Advanced maternal age (>35 years) was associated with a lower risk of preterm labor (3.7% vs 9.2%; RR 0.40, 95% CI 0.21–0.75). Obstetric outcomes were comparable between ET and PV. Conclusions: In this real-world cohort, pregnancies in women with MPNs were associated with measurable rates of thrombotic and obstetric outcomes. LMWH use was associated with a numerically lower risk of miscarriage without statistically significant differences in other outcomes. These findings provide contemporary outcome estimates and may inform risk stratification and future prospective studies. Limitations include the retrospective design, potential misclassification due to inherent limitation of the database, limited MF representation, and inability to assess disease activity, aspirin use, or pregnancy-specific dosing strategies.
Naser et al. (Wed,) studied this question.