Final answer:
Breast tenderness is classified as a presumptive sign of pregnancy, which indicates changes a woman experiences that may suggest pregnancy but are not certain indicators of it.
Step-by-step explanation:
Breast tenderness is classified as a presumptive sign of pregnancy. Presumptive signs are those that are experienced by the woman herself and may be changes associated with pregnancy but are not definitive. During normal hormonal fluctuations, breast tissue responds to changing levels of estrogen and progesterone, leading to swelling and tenderness. This condition becomes more pronounced if pregnancy occurs, due to the further development of the mammary tissue and enlargement of the breasts, which are fueled by the increased hormones required to support the pregnancy.