Hypertensive disorders and severe obstetric morbidity in the United States.

OBJECTIVE To examine trends in the rates of hypertensive disorders in pregnancy and compare the rates of severe obstetric complications for delivery hospitalizations with and without hypertensive disorders. METHODS We performed a cross-sectional study using the 1998-2006 Nationwide Inpatient Sample of the Healthcare Cost and Utilization Project. Logistic regressions and population-attributable fractions were used to examine the effect of hypertensive disorders on severe complications. RESULTS The overall prevalence of hypertensive disorders among delivery hospitalizations increased significantly from 67.2 per 1,000 deliveries in 1998 to 81.4 per 1,000 deliveries in 2006. Compared with hospitalizations without any hypertensive disorders, the risk of severe obstetric complications ranged from 3.3 to 34.8 for hospitalizations with eclampsia/severe preeclampsia and from 1.4 to 2.2 for gestational hypertension. The prevalence of hospitalizations with eclampsia/severe preeclampsia increased moderately from 9.4 to 12.4 per 1,000 deliveries (P for linear trend <0.001) during the period of study. However, these hospitalizations were associated with 38% of hospitalizations with acute renal failure and 19% or more of hospitalizations with ventilation, disseminated intravascular coagulation syndrome, pulmonary edema, puerperal cerebrovascular disorders, and respiratory distress syndrome. Overall, hospitalizations with hypertensive disorders were associated with 57% of hospitalizations with acute renal failure, 27% of hospitalizations with disseminated intravascular coagulation syndrome, and 30% or more of hospitalizations with ventilation, pulmonary edema, puerperal cerebrovascular disorders, and respiratory distress syndrome. CONCLUSION The number of delivery hospitalizations in the United States with hypertensive disorders in pregnancy is increasing, and these hospitalizations are associated with a substantial burden of severe obstetric morbidity. LEVEL OF EVIDENCE III.