Abstract: Corticotropin-releasing hormone（CRH） is a 41-amino-acid neuropeptide that fist identified in the hypothalamus. CRH is detectable in human’s brain peripheral circulation and the maternal-fetal-placental unit. It has been noted that in the third trimester the CRH concentration in maternal plasma increased with advanced gestation, from the 28 menstrua1 week, the women in threatened prematurity groups were significantly higher than normal pregnancy, after the delivery, the CRH concentration decreased quickly. So we can make the conclusion that CRH may be an important factor in onset of delivery by hypothalamus-pituitary-adrenocortex axis,maternal myometrium and other hormones. This article report the mechanisms of placental corticotrophin-releasing hormone（CRH） which is involved in the controlling of the onset of labour.

Key words: Corticotropin-releasing hormone, Hypothalamus-pituitary-adrenocortex axis, Preterm birth, Infection