Acute pyelonephritis is a major cause of infectious morbidity and ICU admissions in pregnancy. In the non-obstetric critical care literature, an “obesity paradox” has been described where increasing Body Mass Index (BMI) is associated with decreased mortality in septic patients admitted to the ICU. Here we study the association between BMI, pyelonephritis in pregnancy, and ICU admission.METHODS:
A retrospective cohort study was performed on all pregnant patients admitted with pyelonephritis for the past 5 years. Data was collected on BMI at presentation, BMI postpartum, disease severity (SIRS, sepsis, or septic shock), and ICU admission. To define the distribution of BMI in our general obstetric population, BMI was recorded for all patients delivering at our institution over a one year period. Patients were grouped by BMI category: normal weight (18.5–24.99 kg/m2), overweight (25–29.99 kg/m2), or obese (greater than 30 kg/m2), and distributions compared by Chi-square test.RESULTS:
The distribution of BMIs in patients with pyelonephritis (n=89) versus general obstetric patients (n=1,076) was significantly different (P<.0001) with 43% versus 11% normal weight, 34% versus 28% overweight, and 23% versus 61% obese, respectively. Postpartum BMIs in patients with pyelonephritis were increased but still significantly different from the general obstetric population (P=.0018). Among patients with pyelonephritis, the odds ratio for ICU admission/shock was 0.25 for obese versus normal/overweight (not significant at P=.2).CONCLUSION:
In this obstetric population, obesity was associated with a decreased incidence of pyelonephritis and a trend towards decreased disease severity suggesting a role for the “obesity paradox” in pregnancy.