Platelet count and indices as postpartum hemorrhage risk factors: a retrospective cohort study

Background: Severe postpartum hemorrhage (SPPH) is the leading cause of maternal mortality and morbidity worldwide. Platelet anomalies frequently occur during pregnancy. However, their role in the etiology of SPPH is largely unknown. Objective: To study the relation between platelet parameters and SPPH. Methods: This retrospective single-center cohort included deliveries between 2009 and 2017. SPPH was defined as ≥1000 ml blood loss within 24 h after delivery. Platelet parameters were measured within 72 h before delivery. Multiple imputation was performed for missing data. Odds ratios were adjusted (aORs) for maternal age, multiple gestation, macrosomia, induction of labor, preeclampsia, and hemolysis, elevated liver enzymes, and low platelets syndrome. Results: A total of 23 205 deliveries were included. Of the 2402 (10.4%) women with thrombocytopenia (<150 × 10 ⁹/L), 10.3% developed SPPH, compared with 7.6% of women with a normal platelet count (aOR: 1.34, 95% CI: 1.14–1.59). Women with a platelet count of <50 × 10 ⁹/L were most at risk (aOR of 2.24 [1.01–4.94]) compared with the reference group with normal platelet counts; the aOR was 1.22 (0.77–1.93) for the 50–99 × 10 ⁹/L platelet count group and 1.31 (1.10–1.56) for the 100–149 × 10 ⁹/L platelet count group. Plateletcrit was associated with SPPH (aOR 1.15 [1.08–1.21] per 0.05% decrease), and, although rarely present, a platelet distribution width (PDW) ≥23% (n = 22) also increased the odds of SPPH (aOR 6.05 [2.29–16.20]). Conclusion: Different degrees of thrombocytopenia were independently associated with the occurrence of SPPH. Despite their relation to SPPH, plateletcrit and a PDW of ≥23% have limited additional value in addition to platelet count.