High Fetal Urocortin Levels at Term and Preterm Labor

Abstract

Placental urocortin has a role in the cascade of events leading to parturition by stimulating myometrial contractility and placental uterotonins secretion. The objective of this study was to evaluate urocortin levels in maternal and fetal [umbilical cord artery (UCA) and vein (UCV)] plasma at term and preterm labor. The study design was a controlled cross-sectional study performed from November 2003 to June 2004. This study was performed at the Division of Obstetrics and Gynecology, University of Siena (Siena, Italy). Plasma samples were collected at term in the absence of labor (TNL; n = 27; 39.3 +/- 0.1 gestational weeks), at term spontaneous vaginal delivery (TL; n = 24; 40.1 +/- 0.2 gestational weeks), and at preterm labor (PTL; n = 19; 32.4 +/- 0.4 gestational weeks). Changes in urocortin mRNA expression were also evaluated in placentas collected from TNL (n = 11), TL (n = 11), and PTL (n = 10). Urocortin levels were measured by specific RIA. Changes in placental mRNA expression were determined by real-time quantitative RT-PCR analysis. Maternal and UCA plasma urocortin levels were significantly (P < 0.0001 for all) higher in TL and PTL than in TNL. Furthermore, UCA concentrations were significantly (P < 0.0001 for all) higher than and correlated with maternal concentrations (TNL: r = 0.45; P < 0.05; TL: r = 0.959; P < 0.0001; PTL: r = 0.7719; P < 0.0001). UCV levels were significantly (P < 0.001) higher in TL and PTL than in TNL and were significantly (P < 0.0001 for all) higher than and significantly (P < 0.0001 for all) correlated with maternal values, but were significantly (P < 0.0001 for all) lower than and correlated with UCA values (TNL: r = 0.9548; P < 0.0001; TL: r = 0.927; P < 0.0001; PTL: r = 0.838; P < 0.0001). Placental urocortin mRNA expression did not differ among TNL, TL, and PTL samples. Fetal urocortin secretion is increased in term and preterm labor. Whether these changes are a consequence rather than a cause of human parturition remains to be addressed.