Final answer:
The third stage of labor lasts from the delivery of the baby until the delivery of the placenta, and it is indicated by various changes in the woman's body.
Step-by-step explanation:
The third stage of labor lasts from the delivery of the baby until the delivery of the placenta.
Detachment of the placenta from the wall of the uterus or separation is indicated by a firmly contracting uterus, change in the shape of the uterus from rounded to oblong, a sudden gush of blood from the introitus, apparent lengthening of the umbilical cord, and the finding of blood clotting or of membranes at the introitus.