Before revision: Fetal ACTH ACTH increases fetal cortisol, which acts by two mechanisms: Increases Prostaglandin F2α which both abolishes the progesterone block, and lowers the oxytocin receptor threshold; and increases expression of relaxin, stretching the pelvic ligaments Increases expression of PTGS in the fetal trophoblast cells PTGS in turn produces prostaglandin E2, which is a catalyst for pregnenalone to C-19 steroids, such as estrogen.
After revision: ,Fetal ACTH ACTH increases fetal cortisol, which acts by two mechanisms: Increases Prostaglandin F2α which both abolishes the progesterone block, and lowers the oxytocin receptor threshold; and increases expression of relaxin, stretching the pelvic ligaments Increases expression of PTGS in the fetal trophoblast cells PTGS in turn produces prostaglandin E2, which is a catalyst for pregnenalone to C-19 steroids, such as estrogen.