Effects of caesarean section on serum levels of NT-proBNP

To determine the effects of delivery by caesarean on serum levels of N-terminal fragment of precursor protein brain-type natriuretic peptide (NT-proBNP).

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.

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).

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.