Preeclampsia Severity and the Risk of Postpartum Hemorrhage: A Systematic Review

Abstract

Postpartum hemorrhage (PPH) remains a leading cause of maternal mortality worldwide, and preeclampsia has long been recognized as a potential contributor to this risk, although evidence on how the risk varies with disease severity remains inconsistent. This review aimed to synthesize current evidence on the association between preeclampsia severity and PPH risk, and to examine whether the magnitude of risk differs between non-severe and severe disease. A systematic literature search was conducted in PubMed, ScienceDirect, and Google Scholar for observational studies, systematic reviews, and meta-analyses reporting this relationship; studies were screened for relevance, methodological quality, and reported effect estimates, and twelve studies meeting the inclusion criteria were retained for qualitative synthesis. Preeclampsia was consistently associated with a higher risk of PPH, with crude and adjusted odds ratios ranging from about 1.3 to 3.1; several large cohorts unexpectedly reported a higher adjusted risk in non-severe than in severe preeclampsia, a pattern linked to differences in labor induction, oxytocin augmentation, and timing of delivery, while uterine atony remained the dominant mechanism, compounded in severe disease by thrombocytopenia, endothelial dysfunction, and, in some cases, coagulopathy. Preeclampsia, regardless of its severity classification, is thus an important and largely modifiable contributor to PPH risk, warranting active management of the third stage of labor and severity-tailored anticipatory planning to reduce PPH-related morbidity in this population.