Patterns of plasma corticotropin-releasing hormone, progesterone, estradiol, and estriol change and the onset of human labor.
BACKGROUND
Clinical prediction of preterm delivery is largely ineffective, and the mechanism mediating progesterone (P) withdrawal and estrogen activation at the onset of human labor is unclear.


OBJECTIVE
Our objectives were to determine associations of rates of change of circulating maternal CRH in midpregnancy with preterm delivery, CRH with estriol (E3) concentrations in late pregnancy, and predelivery changes in the ratios of E3, estradiol (E2), and P.


METHODS
A cohort of 500 pregnant women was followed from first antenatal visits to delivery during the period 2000-2004 at John Hunter Hospital, New South Wales, Australia, a tertiary care obstetric hospital.


METHODS
Unselected subjects were recruited (including women with multiple gestations) and serial blood samples obtained.


METHODS
CRH daily percentage change in term and preterm singletons at 26 wk, ratios E3/E2, P/E3, and P/E2 and the association between E3 and CRH concentrations in the last month of pregnancy (with spontaneous labor onset) were assessed.


RESULTS
CRH percentage daily change was significantly higher in preterm than term singletons at 26 wk (medians 3.09 and 2.73; P = 0.003). In late pregnancy, CRH and E3 concentrations were significantly positively associated (P = 0.003). E3/E2 increased, P/E3 decreased, and P/E2 was unchanged in the month before delivery (medians: E3/E2, 7.04 and 10.59, P < 0.001; P/E3, 1.55 and 0.98, P < 0.001; P/E2, 11.78 and 10.79, P = 0.07).


CONCLUSIONS
The very rapid rise of CRH in late pregnancy is associated with an E3 surge and critically altered P/E3 and E3/E2 ratios that create an estrogenic environment at the onset of labor. Our evidence provides a rationale for the use of CRH in predicting preterm birth and informs approaches to delaying labor using P supplementation.
Smith
Roger
R
Mothers and Babies Research Centre, University of Newcastle, Endocrine Unit, John Hunter Hospital, Newcastle, NSW 2305, Australia. Roger.Smith@newcastle.edu.au
Smith
Julia I
JI
Shen
Xiaobin
X
Engel
Patricia J
PJ
Bowman
Maria E
ME
McGrath
Shaun A
SA
Bisits
Andrew M
AM
McElduff
Patrick
P
Giles
Warwick B
WB
Smith
David W
DW
D015331:Cohort Studies; D003346:Corticotropin-Releasing Hormone / Q000097:blood*; D004958:Estradiol / Q000097:blood*; D004964:Estriol / Q000097:blood*; D005260:Female; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D007745:Labor Onset / Q000097:blood*; D011247:Pregnancy; D011256:Pregnancy Outcome; D011272:Pregnancy, Multiple / Q000097:blood; D047928:Premature Birth / Q000097:blood / Q000175:diagnosis / Q000188:drug therapy; D011374:Progesterone / Q000008:administration & dosage / Q000097:blood*; D011379:Prognosis; D047929:Term Birth / Q000097:blood; D014427:Twins
D011374:Progesterone; D004958:Estradiol; D003346:Corticotropin-Releasing Hormone; D004964:Estriol