Maternal history of recurrent pregnancy loss and long-term risk of thromboembolic events

Background: Recurrent pregnancy loss is a multifactorial disorder with potential underlying maternal hypercoagulability.

Objective: We aimed to investigate whether a history of recurrent pregnancy loss poses an independent risk for future maternal long-term thromboembolic morbidity.

Study design: A population-based study compared the incidence of long-term thromboembolic morbidity in a cohort of women with and without a history of recurrent pregnancy loss. Data were collected from two databases that were cross-linked and merged: a computerized hospitalization database and a computerized obstetrics and gynecology perinatal database. Deliveries occurred between the years 1991-2017. The risk for long-term thromboembolic morbidity was based on the hospital's database and a pre-defined set of ICD codes of thromboembolic related hospitalizations. A Kaplan-Meier survival curve was constructed to compare the cumulative incidence of significant thromboembolic morbidity in the exposed and unexposed groups, and a Cox proportional hazards model, to control for confounders.

Results: During the study period, 123,791 parturients met the inclusion criteria; 6.7 % n = 8247 of which experienced previous recurrent pregnancy loss-the exposed group. The rate of thromboembolic related hospitalizations was almost double in exposed women as compared to non-exposed 1.1 % vs. 0.6 %, OR = 1.8; 95 % 1.4-2.2; p < 0.001). Cumulative thromboembolic event incidence, as depicted in the survival curves, was also significantly higher among patients with recurrent pregnancy loss history (Log rank p < 0.001). The Cox model confirmed recurrent pregnancy loss history to be an independent risk factor for later maternal thromboembolic morbidity, while controlling for maternal age, known thrombophilia, ethnicity, smoking, hypertension, diabetes, and fertility treatment (aHR 1.27, 95 %CI 1.02-1.59, p=0.034).

Conclusion: A history of recurrent pregnancy loss is an independent risk factor for long-term thromboembolic morbidity, even in the absence of known maternal thrombophilia.