Identify a common anatomical change in the body during pregnancy.

During pregnancy, one of the most noticeable anatomical changes is increased lumbar lordosis, which refers to the inward curvature of the lower back. This change occurs primarily as a compensatory adaptation to the growing uterus and the resultant shift in the center of gravity. As the fetus develops and the uterus expands, the body's weight distribution changes, leading to a more pronounced curve in the lumbar region to help maintain balance and posture.

Increased lumbar lordosis helps support the additional weight of the fetus, allowing the mother to stand upright and walk without excessive strain. This adaptation is important for mobility and overall physical stability during pregnancy. As the abdominal cavity enlarges, pregnant individuals often also experience musculoskeletal discomfort, which is linked to these postural changes.

The other options do not accurately reflect common physiological changes associated with pregnancy. For instance, shoulder width does not typically increase, and while the diaphragm may shift slightly due to the enlarged uterus, it does not generally decrease in height. Instead, it may experience more of a functional displacement rather than a structural alteration. Lastly, there is typically no reduction in body fat; rather, women often gain some fat reserves during pregnancy to support fetal growth and prepare for breastfeeding.