C-type natriuretic peptide in complicated pregnancy: increased secretion precedes adverse events.
BACKGROUND
C-type natriuretic peptide (CNP), a vasoactive product of the endothelium, is markedly increased during placentation in ovine pregnancy and is further stimulated by nutrient restriction. Whether CNP products change in human pregnancy is unknown.


OBJECTIVE
The objective of the study was to compare serial changes in maternal plasma CNP peptides during normal pregnancy with changes in pregnancy complicated by adverse events and relate these to fetal growth and placental CNP content.


METHODS
This was a prospective observational study undertaken in a tertiary care center.


METHODS
We studied changes in maternal plasma aminoterminal proCNP (NTproCNP) and CNP at monthly intervals, fetal growth, and placental and umbilical plasma CNP peptides in 51 women, 28 of whom experienced an adverse event and 23 were uneventful. Age matched healthy nonpregnant women served as a reference range for NTproCNP.


RESULTS
Compared with nonpregnant women, maternal plasma NTproCNP in an uneventful pregnancy was significantly reduced from first sampling (16 wk gestation) until 36 weeks. In contrast, in complicated pregnancy, levels did not decline and were significantly higher (P < .001 by ANOVA) than in normal pregnancy from 20 weeks. Highest values occurred in women later developing hypertension and fetal growth disorders. Placental concentration of NTproCNP was unrelated to maternal NTproCNP but strongly correlated with cord plasma levels.


CONCLUSIONS
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.
Departments of Obstetrics and Gynaecology (R.A.R., B.E.P., J.E.G.), Medicine (T.C.R.P., E.A.E.), and Paediatrics (B.A.D.), University of Otago, Christchurch 8140, New Zealand.
Rosemary A
RA
Reid
Timothy C R
TC
Prickett
Barbra E
BE
Pullar
Brian A
BA
Darlow
Joanna E
JE
Gullam
Eric A
EA
Espiner
D000328:Adult; D001724:Birth Weight; D016022:Case-Control Studies; D005260:Female; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D020098:Natriuretic Peptide, C-Type / Q000097:blood* / Q000378:metabolism; D011247:Pregnancy; D011248:Pregnancy Complications / Q000097:blood* / Q000453:epidemiology*; D011256:Pregnancy Outcome / Q000453:epidemiology*; D011379:Prognosis; D055815:Young Adult
D020098:Natriuretic Peptide, C-Type