The Shock Index is a clinical tool to evaluate the hemodynamic status during hemorrhage. The impact of labor and pre-existing anaemia is unknown. The objective was to describe and discuss its clinical utility in this context.
This was a prospective cross-sectional study. The Shock Index (ratio between heart rate and systolic blood pressure) was measured in pregnant women at term, before or during labor. They were stratified according to the presence of anemia.
The median Shock Index was significantly lower in women in labor than in those not in labor (0.72 (IQR: 0.640.83) vs. 0.85 (IQR: 0.800.94); p < 0.001). In women in labor, the Shock Index was not significantly different if anemia was present (0.72 (0.630.83) vs. 0.73 (0.650.82); p = 0.67).
Values of the Shock Index are affected by labor, which may hinder its utility in identifying hemorrhage during this period. However, the values were not altered by maternal anaemia. Therefore, an abnormal postpartum Shock Index should not be attributed to an abnormal antepartum Shock Index due to mild/moderate anemia.