placental clockJoe Segen2016-11-12T00:48:45+00:00
A popular term for the hypothetical timer which some workers believe is intrinsic to the placenta, and controls the length of gestation.
Evidence supporting a placental clock is the inverse relationship between corticotrophin-releasing factor–CRF, which rises and CRF-binding protein–which falls at the end of pregnancy. An abrupt rise in available CRF may be the trigger for parturition in humans. Other hormones to be considered during the placenta’s expiring shelf life include urocortins 1, 2 and 3 and the ratios of oestradiol and oestriol. The concept of a placental clock may be oversimplistic, given that parturition is a complex interplay of hormones and neurochemicals between the placenta, the fetus and the mother.
Synonym Placental timer