Which common physical change occurs in a pregnant woman's body?

During pregnancy, one of the notable physical changes is an increase in breast size. This change occurs primarily due to hormonal fluctuations associated with pregnancy, specifically increased levels of estrogen and progesterone. These hormones stimulate the growth of breast tissue, preparing the breasts for breastfeeding. Additionally, the body may also increase fat deposits in the breast area, further contributing to the increase in size. This physical change is an essential part of the body's preparation to nurture and feed the newborn after delivery.

The other options are less consistent with typical physical changes during pregnancy. Weight loss is generally not expected; in fact, most women gain weight throughout pregnancy due to various factors, including the growing fetus and changes in body composition. A decreased heart rate is not characteristic of pregnancy; rather, it often increases as the body works to support the additional demands placed on it. Lastly, a reduction in appetite can occur for some but is not a universal change—many women experience cravings or increased appetite as their bodies require more nutrients to support fetal development. Therefore, the increase in breast size aligns with the physiological adaptations necessary for successful pregnancy and breastfeeding.