The aim of this study is to examine the BNP levels in preeclamptic women and confounding factors which affect BNP levels.
This was a single-center prospective study from 2013 to 2015. We enrolled 137 preeclamptic women and 773 normal pregnant women. Twin pregnant women were excluded. Serum BNP was examined before delivery: after the diagnosis of preeclampsia in preeclamptic women and at late pregnancy (35–37th gestational week) in normal pregnant women and after delivery: within 4 days postpartum. Echocardiography was also performed at the same timing of BNP monitoring in preeclamptic patients. Baseline characteristics, pre-delivery BNP, and post-delivery BNP between normal pregnant and preeclamptic women were analyzed with independent t-test. Multiple regression analysis was conducted to examine the confounding factors of BNP levels in eclamptic women, and age, pre-pregnancy BMI, serum creatinine, systolic blood pressure, diastolic blood pressure, ejection fraction (EF), and early transmitral velocity/early diastolic velocity of the mitral annulus (E/e’) were used as independent variables. In addition, blood loss at delivery was also included in the analysis of post-delivery BNP.
Age of normal and preeclamptic women were 34.1 mathURL="/science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S2210778916301817&_mathId=si1.gif&_user=111111111&_pii=S2210778916301817&_rdoc=1&_issn=22107789&md5=e4d3d12ecedf25819f358c35c3f0669b" title="Click to view the MathML source">± 5.2 and 33.6 science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S2210778916301817&_mathId=si1.gif&_user=111111111&_pii=S2210778916301817&_rdoc=1&_issn=22107789&md5=e4d3d12ecedf25819f358c35c3f0669b" title="Click to view the MathML source">± 5.8, p = 0.27. BMI were 21.7 science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S2210778916301817&_mathId=si1.gif&_user=111111111&_pii=S2210778916301817&_rdoc=1&_issn=22107789&md5=e4d3d12ecedf25819f358c35c3f0669b" title="Click to view the MathML source">± 4.0 and 23.1 science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S2210778916301817&_mathId=si1.gif&_user=111111111&_pii=S2210778916301817&_rdoc=1&_issn=22107789&md5=e4d3d12ecedf25819f358c35c3f0669b" title="Click to view the MathML source">± 5.3, p < 0.01. Pre-delivery BNP levels were 17.9 science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S2210778916301817&_mathId=si1.gif&_user=111111111&_pii=S2210778916301817&_rdoc=1&_issn=22107789&md5=e4d3d12ecedf25819f358c35c3f0669b" title="Click to view the MathML source">± 13.7 and 82.9 science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S2210778916301817&_mathId=si1.gif&_user=111111111&_pii=S2210778916301817&_rdoc=1&_issn=22107789&md5=e4d3d12ecedf25819f358c35c3f0669b" title="Click to view the MathML source">± 103.6, p < 0.01. Post-delivery BNP levels were 42.5 science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S2210778916301817&_mathId=si1.gif&_user=111111111&_pii=S2210778916301817&_rdoc=1&_issn=22107789&md5=e4d3d12ecedf25819f358c35c3f0669b" title="Click to view the MathML source">± 35.8 and 63.1 science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S2210778916301817&_mathId=si1.gif&_user=111111111&_pii=S2210778916301817&_rdoc=1&_issn=22107789&md5=e4d3d12ecedf25819f358c35c3f0669b" title="Click to view the MathML source">± 71.8, p < 0.01. The results of multiple regression analysis of pre-delivery and post-delivery BNP are described in the Table. Pre-delivery BNP was related with EF, which is an indicator of left ventricular systolic function. Pre-pregnancy BMI, serum creatinine, and systolic blood pressure also affected pre-delivery BNP levels. On the other hand, post-delivery BNP was related with E/e’, which is an indicator of left ventricular diastolic function. Pre-pregnancy BMI and blood loss at delivery significantly affected post-delivery BNP levels.
BNP levels deteriorated after delivery in normal pregnant women while BNP levels improved after delivery in preeclamptic women. Delivery causes a stress on maternal heart, but recovery from preeclampsia had bigger impact on BNP levels. Although BNP levels reflected maternal cardiac function, the effect of pre-pregnancy BMI, kidney function, blood pressure, and blood loss at delivery should be considered when using BNP monitoring in preeclamptic women. Besides, pre-pregnancy BMI was negatively related with BNP levels although obesity is a risk factor of heart failure.