Final answer:
With fetal descent during childbirth, the fundus of the uterus moves down, reducing pressure on the diaphragm and making breathing easier for the mother.
Step-by-step explanation:
With fetal descent, the uterus moves downward, and the fundus no longer presses on the diaphragm, which eases breathing. The muscular walls of the uterus, especially the thick layer known as myometrium, contract to push the baby through the cervix and vagina during labor. Before labor, as the fetus grows, the uterus expands significantly and can exert pressure on surrounding structures like the diaphragm. The fundus, being the portion of the uterus superior to the opening of the uterine tubes, moves upward during pregnancy but descends as childbirth approaches, reducing pressure on the diaphragm and thereby easing breathing for the expectant mother.