Brain natriuretic peptide in term pregnancy.

To determine the normal range of serum brain natriuretic peptide (BNP) in uncomplicated, singleton term pregnant patients. Serum for analysis of BNP was drawn at admission to labor and delivery (= 104), prior to administration of intravenous fluid. Median BNP was 20 pg/mL, with an interquartile range of 20 pg/mL (range 5-70 pg/mL; or a mean ± standard deviation [SD] of 23 ± 16 pg/mL). Brain natriuretic peptide negatively correlated with prepregnant (r = -.24, P < .05) and pregnant weight (r = -26, P < .01) and with heart rate (r = -.35, P < 0.001); heart rate was also positively correlated with BMI (r = .32). Brain natriuretic peptide levels were higher in Hispanic than African American women, independent of body mass index (BMI) and heart rate. Brain natriuretic peptide values found in term pregnant patients are similar to those of prepregnant women of reproductive age. Brain natriuretic peptide levels appear to be set by conditions present in the prepregnant condition and maintained, despite changes in plasma volume, systemic vascular resistance, and cardiac output.