C-Type Natriuretic Peptide in Complicated Pregnancy: Increased Secretion Precedes Adverse Events

Abstract

Maternal NTproCNP is significantly raised in women who later exhibit a range of obstetric adverse events. Lack of association with placental concentrations suggests that these changes represent an adaptive response within the maternal circulation to a threatened nutrient supply to the fetus.

Effects of pre‐eclampsia and fetal growth restriction on C‐type natriuretic peptide

“…In women with GHT plus SGA (but without evidence of pre‐eclampsia or other adverse events), NTproCNP levels do not differ from control values at either 14–16 or 19–21 weeks of gestation, but increase in late pregnancy (34–36 weeks of gestation) to values similar to pre‐eclampsia, and exceed those in controls at the same gestational age. As only five women with GHT plus SGA had blood sampled in late pregnancy, these findings are preliminary, but are virtually identical to the results we have previously reported . In the current study NTproCNP was unrelated to blood pressure at any time point in GHT with SGA.…”

“…As found previously, plasma NTproCNP concentrations show a modest increase in late gestation in uneventful pregnancy. No association was found with maternal blood pressure, height, or BMI early in gestation in normal pregnancies; however, in late gestation a significant positive association of NTproCNP was found with diastolic blood pressure and MAP, even though blood pressure recordings were consistently within normal limits throughout gestation in this group.…”

“…As only five women with GHT plus SGA had blood sampled in late pregnancy, these findings are preliminary, but are virtually identical to the results we have previously reported. 11 In the current study NTproCNP was unrelated to blood pressure at any time point in GHT with SGA. Taken together with the finding that MAP in GHT with SGA was significantly lower than in women with preeclampsia at the time of diagnosis, yet maternal NTproCNP in the two groups did not differ, the results suggest that additional factors arising from restricted fetal growth may also contribute to elevated maternal levels in late gestation, and now need further study.…”

“…found that maternal plasma CNP concentration in women with pre‐eclampsia or GHT did not differ from normal pregnancy values when measured at 26–39 weeks of gestation . The latter finding is not surprising given the rapid degradation of CNP and the poor correlation with concurrent plasma levels of NTproCNP in human pregnancy . Despite these negative findings, evidence ex vivo shows that shear stress, likely to increase with the increasing haemodynamic load in pregnancy, upregulates NPPC gene expression and increases CNP protein production.…”

“…18 The latter finding is not surprising given the rapid degradation of CNP and the poor correlation with concurrent plasma levels of NTproCNP in human pregnancy. 11 Despite these negative findings, evidence ex vivo shows that shear stress, likely to increase with the increasing haemodynamic load in pregnancy, 19 upregulates NPPC gene expression and increases CNP protein production. Connecting these findings is the greatly augmented and selective up-regulation of the CNP receptor (NPRB) and content of CNP in the ovine uterine arterial endothelium in late gestation.…”