Final answer:
The fundus is the upper part of the uterus that can rise after childbirth.
Step-by-step explanation:
The fundus is the uppermost part of the uterus, located above the body of the uterus. After childbirth, the fundus can rise to approximately 1 cm above the umbilicus within 12 hours. By the sixth postpartum day, it is normally located halfway between the umbilicus and the symphysis pubis.
At the end of the third stage of labor, the uterus is in the midline, approximately 2 cm below the level of the umbilicus with the fundus resting on the sacral promontory. At 24 hours after birth, the uterus is about the same size as it was at 20 weeks' gestation, not 12 hours.