Prospective observational study of amino-terminal brain natriuretic peptide levels in obese and non-obese women during pregnancy.
OBJECTIVE: NT-proBNP, a marker of ventricular dysfunction, varies by BMI outside of pregnancy. This study aimed to determine whether obesity affects NT-proBNP levels in pregnancy. STUDY DESIGN: This was a prospective observational study of healthy pregnant people in the 3rd trimester and postpartum (PP). Subjects were excluded if they had significant medical comorbidities or if their fetuses had anomalies, growth restriction or aneuploidy. NT-proBNP was measured at 28 weeks (3TM), prior to delivery (PD), 1-2 days PP (IPP), and 4-6 weeks PP (DPP). LogNT-proBNP levels were analyzed using linear mixed effects models, including BMI < or ≥30, time, and time-by-BMI interactions. RESULTS: Fifty-five people (28 [51%] with BMI ≥ 30 and 27 [49%] with BMI < 30) were enrolled. A greater proportion of obese than non-obese subjects developed hypertensive disorders of pregnancy (50% vs 15%, p=0.010) and obese subjects had higher systolic blood pressures at all time points (p<0.05). NT-proBNP levels (median [IQR] in pg/mL) were 18 (6-28) vs 26 (17-48) at 3TM, 16 (3-38) vs 43 (21-60) at PD, 58 (20-102) vs 63 (38-155) at IPP, and 33 (27-56) vs 23 (8-42) at DPP for obese compared to non-obese subjects. In linear mixed effects models, logNT-proBNP was lower in obese subjects at 3TM (β=-0.89 [95% confidence interval -1.51, -0.26]) and PD (β=-1.05 [95% CI -1.72, -0.38]). The logNT-proBNP trends over time differed by BMI category, with higher values in obese subjects at both postpartum time points compared to the 3TM (IPP β=1.24 [95% CI 0.75, 1.73]); DPP β=1.08 [95% CI 0.52, 1.63]), but only IPP for non-obese subjects (β=0.87 [95% CI 0.36, 1.38]). CONCLUSIONS: Obese subjects had lower NT-proBNP levels than non-obese subjects during pregnancy, but not postpartum. The prolonged postpartum elevation in NT-proBNP in obese subjects suggests that their postpartum cardiac recovery may be more prolonged.
Denoble, A; Moyett, J; Goldstein, S; Ward, CC; Truong, T; Erkanli, A; James, A; Grotegut, C
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