the rise in plasma acth concentrations , as pregnancy advances , in spite of increasing levels of plasma cortisol , estrogens , and progesterone , is suggestive of the possibility that a source of acth exists that is not subject to negative feedback control , that the clearance of free cortisol increases as pregnancy advances , or that there is an alteration in the metabolism of the acth precursor protein produced by the pituitary and/or placenta .
C0033308
progesterone
C0032961
pregnancy