Japanese obstetrical hemorrhage recommendations state that not only pregnant women with an obstetrical disseminated intravascular coagulation (DIC) score ≥ 8 points but also those with fibrinogen levels ≤ 1.5 g/L have a high risk of maternal death and warrant blood transfusion. Our aim was to demonstrate the potential of fibrinogen levels ≤ 1.5 g/L as predictors of a Japanese obstetrical DIC score of ≥ 8. We included 595 participants with blood loss ≥ 1000 mL during vaginal delivery or ≥ 2000 mL during cesarean delivery. The frequency and volume of red blood cell (RBC), fresh-frozen plasma, platelet concentrate (PC), and fibrinogen administration in women with a DIC score of ≥ 8 and fibrinogen levels of ≤ 1.5 g/L were significantly higher than controls (P < 0.0001). Multivariate analysis demonstrated that a score of ≥ 3 was associated with RBC or fibrinogen administration and a score of ≥ 5 was associated with PC transfusion. Fibrinogen levels ≤ 1.89 g/L and ≤ 2.44 g/L were associated with PC transfusion and fibrinogen administration, respectively. Fibrinogen levels ≤ 1.5 g/L may have similar potential to a DIC score of ≥ 8 points for detecting obstetrical DIC in Japan.