Factors associated with increased levels of brain natriuretic peptide and cardiac troponin I during the peripartum period

Background We aimed to investigate the values and the changes of brain natriuretic peptide (BNP) and cardiac troponin in pregnant women. Methods and results We prospectively collected the data of 405 pregnant women who were treated at Japanese general hospital between 2012 and 2013. We analyzed their laboratory data and echocardiographic findings during the third trimester (28-30 weeks' gestation) and within 4 days of delivery. In addition, we evaluated the factors associated with elevation of BNP and cardiac troponin I (cTnI) levels. The pregnant women were 33.8 +/- 5.0 years old and the prevalence of pregnancy induced hypertension (PIH) and placental abnormality was 4.2% and 2.5%, respectively. BNP levels increased after delivery (13.2 pg/mL vs. 23.5 pg/mL; P < 0.001), correlated with increased left ventricular diastolic dimension (P = 0.035), left atrial dimension (P < 0.001), and decreased hemoglobin (P < 0.001). Moreover, cTnI levels increased to over 0.015 ng/mL after delivery in 4.0% of pregnant women. In multivariate analysis, PIH (OR: 18.71, P = 0.003), placental abnormality (OR: 26.78, P = 0.007), and decreased hemoglobin after delivery (OR: 2.59, P < 0.001) were the factors associated with elevated cTnI. Conclusions BNP levels increased in association with cardiac chamber enlargement and decreased hemoglobin after delivery. Additionally, the factors affecting elevated cTnI levels were related to labor and delivery.