Usefulness of brain-type natriuretic peptide (BNP) levels in pregnancy

Natriuretic peptides, such as active brain-type natriuretic peptide (BNP) and inert N-terminal pro-B-type natriuretic peptide (NT-proBNP), are hormones secreted by the heart in response to increased intraventricular pressure and circulating blood volume. Physiological cardiovascular adaptations during pregnancy result in an increase in BNP secretion. In non-pregnant populations, these peptides are well-established markers for diagnosing heart failure and assessing cardiac risk; however, their clinical usefulness in pregnancy and cardiovascular risk assessment is limited. This paper aims to summarise the possible uses of BNP in pregnancy based on the available literature and research.

We searched Medline, PUBMED, Cochrane Central Register of Controlled Trials, and Cochrane Database of Systematic Reviews for English-language studies published regarding BNP and pregnancy.

BNP and NT-proBNP are valuable markers for diagnosing and predicting cardiac complications in pregnancy, including heart failure, pre-eclampsia, and peripartum cardiomyopathy, and for risk stratification in women with adverse pregnancy outcomes. Recommended upper limits are 50 pg/ml for BNP across all trimesters and 200 pg/ml (first and second trimester) and 150 pg/ml (third trimester) for NT-proBNP. A BNP >100 pg/ml demonstrates high diagnostic accuracy (sensitivity 98%, specificity 92%, PPV 92%, NPV 97%) for cardiac complications. In addition, BNP used in conjunction with sFlt-1/PlGF ratio tests, has improved the predictive capability of delivery in pre-eclampsia (p = 0.011).

BNP and NT-proBNP are widely used in emergency settings to differentiate cardiac from non-cardiac causes of dyspnoea and heart failure, but their use in pregnancy-specific conditions remains. The fluctuation of BNP levels with pre-existing cardiac, renal disease and obesity needs further evaluation to identify a useful cut-off for the use of BNP in pregnancy.