Effects of caesarean section on serum levels of NT-proBNP

Objective To determine the effects of delivery by caesarean on serum levels of N-terminal fragment of precursor protein brain-type natriuretic peptide (NT-proBNP). Methods Serum NT-proBNP levels were determined longitudinally at 24 and 36 weeks of gestation (GW) and on post-partum day 3 and month 1 (PPD3 and PPM1, respectively) in 78 women with normotensive singleton pregnancies. Thirty-nine women underwent caesarean delivery. Plasma renin activity (PRA) and plasma aldosterone concentration (PAC) were determined on PPD3. Effects of maternal demographic characteristics on NT-proBNP levels were also analysed. Results NT-proBNP levels (pg/ml) either in pregnancy or on PPM1 did not differ between women with vaginal and caesarean deliveries (44 +/- 24 vs 41 +/- 30, 24 GW; 37 +/- 22 vs 29 +/- 22, 36 GW; 43 +/- 28 vs 39 +/- 24, PPM1, respectively). Levels on PPD3 were significantly higher (94 +/- 105 vs 247 +/- 186, P < 0.0001) in women with caesarean delivery. Among women with caesarean delivery, a larger rise of NT-proBNP on PPD3 occurred in nulliparous than in multiparous women (319 +/- 232 vs 185 +/- 107, P = 0.023), while no rise occurred among multiparous women with vaginal delivery (108 +/- 115 vs 47 +/- 27). NT-proBNP levels on PPD3 were significantly and negatively correlated with PRA, PAC and maternal weight loss after childbirth on PPD3. These 3 variables on PPD3 were significantly lower in women undergoing caesarean than vaginal delivery (0.8 +/- 0.4 vs 1.9 +/- 1.4 ng/ml/h for PRA; 70 +/- 38 vs 136 +/- 88 pg/ml for PAC; 2.7 +/- 1.2 vs 4.3 +/- 1.1 kg for weight loss, each P < 0.0001). Conclusions The transient post-partum rise in serum NT-proBNP may reflect transient volume overload after parturition and is remarkable in nulliparous women, especially after caesarean section.