Trends in postpartum hemorrhage, associated risk factors, and severe maternal outcomes in a multihospital health system, 2016-2023: a retrospective cohort study.

BACKGROUND: Reported increases in postpartum hemorrhage (PPH) raise concerns for maternal risk and resource needs, but contemporary multicenter trends and severe outcomes remain uncertain. OBJECTIVE: To quantify trends in PPH and severe PPH and identify factors associated with PPH to inform hemorrhage surveillance and preparedness. STUDY DESIGN: Retrospective cohort of all deliveries across eight hospitals (2 tertiary, 6 community) in a U.S. health system (2016-2023). PPH was defined as blood loss ≥1000 mL or red blood cell transfusion within 24 hours, and severe PPH as PPH plus ≥1 severe morbidity indicator. Temporal trends were evaluated using logistic regression. Risk-factor associations were estimated using modified Poisson regression with robust standard errors clustered by maternal identifier. RESULTS: Among 115,087 deliveries, PPH increased from 8.1% to 10.4% (absolute increase, 2.3 percentage points; P for trend <.001), and severe PPH increased from 0.9% to 1.3% (absolute increase, 0.3 percentage points; P for trend <.001). Labor induction increased (24.0% to 37.2%), as did hypertensive disorders, higher obstetric comorbidity, and prior PPH. PPH was most strongly associated with placenta accreta spectrum (aRR, 3.51; 95% CI, 3.26-3.78), multiple gestation (aRR, 2.08; 95% CI, 1.96-2.21), operative vaginal delivery (aRR, 2.03; 95% CI, 1.84-2.25), and prolonged second stage (aRR, 1.76; 95% CI, 1.67-1.84). Among PPH cases, intensive care unit admission occurred in 2.0%, hysterectomy in 2.3%, and maternal death in 0.2%. CONCLUSION: In this multicenter network, PPH and severe PPH increased from 2016 to 2023, while severe outcomes among PPH cases remained uncommon. These data provide benchmarks for hemorrhage surveillance, preparedness, and resource planning across delivery settings.