how does the placenta detaches from the uterus after birth
Placental expulsion As the fetal hypothalmus matures activation of the HPA axis (hypothalmic-pituitary-adrenal axis) initiates labour though two hormonal mechanisms. The end pathway of both mechanisms leads to myometrial contractions a mechanical cause of placental separation, from the shear force, contractile and involution changes in the uterus distorting the placentome.
Childbirth The vagina is called a 'birth canal' when the baby enters this passage.