The golden hour for postpartum hemorrhage: Results from a prospective cohort study.

Objective: To evaluate the predictive capacity of vital signs for the diagnosis of postpartum hemorrhage (PPH).

Methods: A prospective cohort study performed at the University of Campinas, Brazil, between February 2015 and March 2016 with women who delivered vaginally. Vital signs and postpartum bleeding were collected over 24 h. Exploratory data analysis was performed plus receiver operating characteristic curve analysis where the areas under the curve was used to determine the best cutoff points for sensitivity, specificity, likelihood ratio, and diagnostic odds ratio.

Results: For the 270 women recruited, mean blood loss after 120 min was 427.49 ± 335.57 ml, while 84 (31.1%) and 22 (8.1%) women had blood loss ≥500 and ≥1000 ml, respectively. Heart rate cutoff point of 105 bpm measured between 21-40 min after birth identified blood loss ≥1000 ml with 90% specificity. A shock index (SI) of 0.965 at 41-60 min after birth identified blood loss ≥500 and ≥1000 ml within 2 h with approximately 95% specificity.

Conclusion: Shock index and heart rate measured after birth showed high specificity with low sensitivity to identify PPH. In clinical practice, "The rule of 1s" should receive special attention: SI ≥1, or heart rate >100 bpm, or estimated blood loss ≥1 L.