High fetal urocortin levels at term and preterm labor.

CONTEXT: Placental urocortin has a role in the cascade of events leading to parturition by stimulating myometrial contractility and placental uterotonins secretion. OBJECTIVE: 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. DESIGN: The study design was a controlled cross-sectional study performed from November 2003 to June 2004. SETTING: This study was performed at the Division of Obstetrics and Gynecology, University of Siena (Siena, Italy). PATIENTS: 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). INTERVENTION: Urocortin levels were measured by specific RIA. Changes in placental mRNA expression were determined by real-time quantitative RT-PCR analysis. RESULTS: 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. CONCLUSIONS: 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.