Mild Thrombocytopenia at Admission to Labor and Delivery: Implications for Postpartum Hemorrhage.

BACKGROUND Postpartum hemorrhage remains a leading cause of severe maternal morbidity and mortality. The association between mild thrombocytopenia and postpartum blood loss or red blood cell transfusion has not been well studied.

OBJECTIVE To evaluate whether mild thrombocytopenia at admission to labor and delivery is associated with increased rates of postpartum hemorrhage and packed red blood cell transfusion.

STUDY DESIGN The authors performed a retrospective cohort study of pregnancies delivered within a large health maintenance organization from 2008 to 2020. Maternal characteristics and outcomes of those with mild thrombocytopenia were compared to those with typical platelet levels before delivery. The primary outcome was the rate of red blood cell transfusion. Secondary outcomes included quantity of red blood cell transfusion, postpartum hemorrhage, additional procedures performed, and use of uterotonic medications. Statistical analysis was done using χ2 or Mann-Whitney U test. A multivariable logistic regression was also performed.

RESULTS Data from a total of 305,794 pregnancies were included in this study. Mild thrombocytopenia was associated with a small but statistically significant increase in postpartum red blood cell transfusion compared with typical platelet levels (1.2% vs 0.9%, P < .0001). Mild thrombocytopenia was also associated with a higher rate of 2 or more red blood cell transfusions (0.33% vs 0.19%), postpartum hemorrhage (2.4% vs 2.0%), use of uterotonics, and additional procedures performed (all P values < .05). These outcomes all remained statistically significant after adjusting for confounding variables.

CONCLUSIONS Mild thrombocytopenia prior to delivery is associated with a small increased chance of red blood cell transfusion, postpartum hemorrhage, uterotonic use, and the need for additional procedures postpartum.