Because maternal plasma corticotrophin-releasing factor (CRF) levels increase during the last weeks of pregnancy and at parturition, the present study evaluated whether placental mRNA expression of CRF and CRF-binding protein (CRF-BP) are modified in preterm delivery. A group of 30 women with singleton pregnancies were enrolled in the study. A placental tissue specimen was collected from pregnant women (1) at term after cesarean delivery (39.3 +/- 0.1 gestational weeks; n = 10), (2) at term after spontaneous vaginal delivery (40.1 +/- 0.2 gestational weeks; n = 10), or (3) at preterm delivery (32.4 +/- 0.4 gestational weeks; n = 10). Changes of placental mRNA expression were evaluated by real-time quantitative reverse transcriptase polymerase chain reaction analysis. Placental CRF mRNA expression at term (P < .001) and preterm delivery (P < .001) was significantly higher than in cesarean delivery and highest in preterm placentas. With respect to CRF-BP, no significant difference in placental mRNA expression was observed among samples collected after term or preterm delivery and cesarean delivery. The present study showed for the first time that both term and preterm labor are associated with increased expression of placental CRF but not CRF-BP mRNA.