Prevalence and Correlates of Elevated NT-proBNP in Pregnant Women

Quick Takes

  • The purpose of this study was to investigate the dynamics of NT-proBNP levels during pregnancy and their relationship with factors such as BMI and systolic BP.
  • This study utilized a cross-sectional design with a nationally representative sample of pregnant and nonpregnant women from the US.
  • The findings revealed that NT-proBNP levels were significantly lower during pregnancy, particularly in the second trimester, and were inversely associated with BMI and systolic BP, suggesting that these factors must be considered when assessing NT-proBNP levels in pregnant women.

Study Questions:

How do N-terminal pro–B-type natriuretic peptide (NT-proBNP) levels change throughout pregnancy and what are their determinants?


This observational, cross-sectional study utilized the data from the National Health and Nutrition Examination Survey (NHANES) from 1999–2004, which is a nationally representative sample of the US civilian population. NT-proBNP levels were measured in stored serum from 546 pregnant women aged 20-40 years and compared with nonpregnant women of the same age range (n = 1,588). Participants with a history of cardiovascular disease or missing variables of interest were excluded. Demographic characteristics, cardiovascular risk factors, and NT-proBNP levels were compared between pregnant and nonpregnant women and among pregnant women across trimesters. Multivariable linear regression was used to evaluate the associations of body mass index (BMI) and systolic blood pressure (SBP) with NT-proBNP.


The study included 2,134 women (546 pregnant). The mean age was 30.2 years, and mean BMI was 27.6 kg/m2. Among pregnant women, median NT-proBNP levels were 68 ng/mL in the first trimester, 53 ng/mL in the second trimester, and 36 ng/mL in the third trimester. For nonpregnant women, the median NT-proBNP level was 48 ng/mL. Elevated NT-proBNP (>125 pg/mL) was present in 20.0% of women in the first trimester, 2.4% in the third trimester, and 8.0% of nonpregnant women. After adjusting for cardiovascular risk factors, NT-proBNP was consistently higher in the first trimester compared to nonpregnant women. Among pregnant women, NT-proBNP was consistently lower in the third trimester compared to the first trimester across all models. BMI and SBP were inversely associated with NT-proBNP in the second and third trimesters.


NT-proBNP levels were higher in the first trimester of pregnancy compared to nonpregnant women and women in later trimesters. BMI and SBP were associated with lower NT-proBNP levels in the second and third trimesters.


This study offers insights into the dynamic nature of NT-proBNP levels during pregnancy and its relationship with clinical factors. Its findings have implications for the interpretation and use of NT-proBNP as a diagnostic tool in pregnant women without cardiovascular disease, suggesting that factors such as trimester, BMI, and blood pressure must be considered when assessing NT-proBNP levels. The nationally representative sample of diverse pregnant and nonpregnant women from across the US and standardized measurements conducted by trained personnel serve as major strengths of this study.

However, the study has some limitations. A major limitation is the lack of longitudinal data on the women throughout their pregnancies, making it difficult to confirm observed differences in NT-proBNP levels as true physiological changes. Residual confounding, despite rigorous adjustments for demographic and cardiovascular risk factors, could also impact the results. Additionally, the absence of cardiac imaging data to correlate NT-proBNP findings with structural and functional myocardial changes in pregnancy and the inability to identify women with pregnancy-induced hypertension are limitations that must be acknowledged. Further research with longitudinal data and cardiac imaging could provide a more comprehensive understanding of NT-proBNP dynamics during pregnancy.

Clinical Topics: Prevention, Hypertension

Keywords: Biomarkers, Blood Pressure, Body Mass Index, Hypertension, Natriuretic Peptide, Brain, Pregnancy, Pregnancy Trimester, First, Pregnant Women, Risk Factors, Secondary Prevention

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