Prenatal hypertension as the risk of eclampsia, HELLP syndrome, and critical obstetric hemorrhage.

Critical bleeding is a common cause of maternal mortality in obstetric patients. However, the non-obstetric factors underlying critical obstetric bleeding remain uncertain. Therefore, this study aimed to clarify the impact of chronic hypertension on obstetric hemorrhage by evaluating a nationwide administrative database in Japan. Women who gave birth between 2018 and 2022 were enrolled. The primary outcome was critical hemorrhage requiring massive red blood cell (RBC) transfusion during childbirth. In total, 354, 299 eligible women were selected from the database. The maternal mortality rate was >1.0% among those who received a massive RBC transfusion (≥4000 cc), and this amount was used as the cutoff of the outcome. Critical hemorrhage was less frequent with elective Caesarean section (CS) compared with vaginal childbirth or emergent CS (odds ratio [OR], 0.38; 95% confidence interval, 0.30-0.47). Multiple logistic regression analysis adjusting for these obstetric risks revealed that a higher maternal age (adjusted OR [aOR] per 1 year, 1.07 [1.05-1.09]); oral medications with prednisolone (aOR, 2.5 [1.4-4.4]), anti-coagulants (aOR, 10 [5.4-19]), and anti-platelets (aOR, 2.9 [1.3-6.4]); and a prenatal history of hypertension (aOR, 2.5 [1.5-4.4]) and hypoproteinemia (aOR, 5.8 [1.7-20]) are the risks underlying critical obstetric hemorrhage. Prenatal history of hypertension was significantly associated with obstetric disseminated intravascular coagulation (OR, 1.9 [1.5-2.4]); Hemolysis, Elevated Liver enzymes, and Low platelet count (HELLP) syndrome (OR, 3.3 [2.7-4.2]); and eclampsia (OR, 6.1 [4.6-8.1]). In conclusion, a maternal prenatal history of hypertension is associated with the development of HELLP syndrome, eclampsia, and resultant critical hemorrhage. The incidence of HELLP syndrome and eclampsia increased more than fivefold in the presence of prenatal hypertension. However, the likelihood of subsequently developing DIC or experiencing critical bleeding did not change by the presence of prenatal hypertension.