B-type natriuretic peptide in low-risk pregnancy and pregnancy with congenital heart disease.

OBJECTIVE: To perform a longitudinal assessment of B-type natriuretic peptide (BNP) and its association with cardiac function in low-risk pregnant women and in pregnant women with congenital heart disease (CHD).

METHODS: Longitudinal study in low-risk pregnancy and pregnancy in women with CHD seen at 10-14, 18-22, and 30-34 weeks of pregnancy for BNP quantification and exercise studies using impedance cardiography (ICG).

RESULTS: Forty-three low-risk women with longitudinal samples (129 samples, 43 in each trimester) and 30 pregnant women with CHD with convenience samples (first trimester, five samples; second trimester, 20 samples; third trimester, 21 samples) were included. Women with CHD delivered earlier by 6 days (P = 0.002) and their newborns had lower birth weight independent of gestational age (birth weight centile 30.0 vs 55.0, P = 0.005). In low-risk women, BNP levels were lower in the third trimester (P < 0.001). There were no statistically significant differences in BNP concentrations across trimesters in the CHD group, no differences in BNP concentrations between the two groups, and no significant correlations between BNP concentration in each trimester with cardiac output, stroke volume, or heart rate (at rest/with exercise).

CONCLUSION: This study assessed BNP longitudinally in the first, second and third trimesters in singleton low-risk pregnancy, and showed that BNP concentration decreased with advancing gestational age, with no participants with levels greater than 40.0 pg/mL in the third trimester. BNP concentrations were similar in women with and without congenital heart disease. We found no correlation between circulating levels of BNP and maternal hemodynamics at rest or with exercise measured by ICG to support its use as a marker of cardiac function.