Final answer:
Back labor is often caused by the weight and size of the fetus, hormonal changes during pregnancy that loosen pelvic ligaments, and improper lifting techniques that strain muscles and damage the spine.
Step-by-step explanation:
Persistent and poorly relieved back pain, often referred to as back labor, can be caused by a variety of factors, particularly during pregnancy. One of the reasons why pregnant women often suffer from back strain late in their pregnancy is the increasing weight and size of the developing fetus. This can lead to a shift in the center of gravity, causing the mother to adjust her posture and place additional strain on the back muscles. Furthermore, the hormonal changes during pregnancy can lead to the loosening of ligaments in the pelvic area, which can also contribute to instability and pain in the back.
Lifting objects improperly can also cause muscle strain and potentially damage discs and vertebrae, leading to back pain. The increased forces placed on the back muscles and spine during such lifting can result in significant discomfort.