title: A placental clock controlling the length of human pregnancy.
abstract: We report the existence of a 'placental clock', which is active from an early stage in human pregnancy and determines the length of gestation and the timing of parturition and delivery. Using a prospective, longitudinal cohort study of 485 pregnant women we have demonstrated that placental secretion of corticotropin-releasing hormone (CRH) is a marker of this process and that measurement of the maternal plasma CRH concentration as early as 16-20 weeks of gestation identifies groups of women who are destined to experience normal term, preterm or post-term delivery. Further, we report that the exponential rise in maternal plasma CRH concentrations with advancing pregnancy is associated with a concomitant fall in concentrations of the specific CRH binding protein in late pregnancy, leading to a rapid increase in circulating levels of bioavailable CRH at a time that coincides with the onset of parturition, suggesting that CRH may act directly as a trigger for parturition in humans.
authors.affiliation: Maternal Health Research Centre, John Hunter Hospital, Newcastle, NSW, Australia.
authors.forename: M
authors.initials: M
authors.lastname: McLean
authors.forename: A
authors.initials: A
authors.lastname: Bisits
authors.forename: J
authors.initials: J
authors.lastname: Davies
authors.forename: R
authors.initials: R
authors.lastname: Woods
authors.forename: P
authors.initials: P
authors.lastname: Lowry
authors.forename: R
authors.initials: R
authors.lastname: Smith
mesh_terms: D001683:Biological Clocks / Q000502:physiology*; D002352:Carrier Proteins / Q000097:blood; D003346:Corticotropin-Releasing Hormone / Q000097:blood*; D005260:Female; D006801:Humans; D007752:Obstetric Labor, Premature / Q000503:physiopathology; D010920:Placenta / Q000502:physiology; D011247:Pregnancy / Q000097:blood*
chemical_list: D002352:Carrier Proteins; C067133:corticotropin releasing factor-binding protein; D003346:Corticotropin-Releasing Hormone