Final answer:
The stage of labor that begins with the expulsion of the placenta is Stage Three.
Step-by-step explanation:
The stage of labor that begins with the expulsion of the placenta and ends with postpartum stabilization is Stage Three.
During stage one, the cervix thins and dilates. This is necessary for the baby and placenta to be expelled during birth. The cervix will eventually dilate to about 10 cm. During stage two, the baby is expelled from the uterus. The uterus contracts and the mother pushes as she compresses her abdominal muscles to aid the delivery. The last stage is the passage of the placenta after the baby has been born and the organ has completely disengaged from the uterine wall.