Which physical examination finding typically appears by 12 weeks of pregnancy?

Chadwick's sign is a physical examination finding that refers to the bluish discoloration of the cervix, vagina, and labia resulting from increased blood flow and vascular congestion in these areas during early pregnancy. This sign typically becomes noticeable around the 6th to 8th week of gestation, and it can be recognized by 12 weeks of pregnancy as well. It is an early indicator of pregnancy and reflects the physiological changes occurring in a woman's body to accommodate fetal development.

While the other options present various findings, they are either not as early in the pregnancy or are less directly associated with the physical examination of a pregnant patient at this stage. For instance, the uterus typically becomes palpable at the level of the umbilicus around 20 weeks of gestation. Blood pressure changes can occur during pregnancy, but a decrease below normal levels is not definitive or consistent by 12 weeks. Hyperreflexia is not a typical finding associated with pregnancy in the early stages and would not be expected in the examination of a patient at this point. Thus, Chadwick's sign serves as a significant early clue during the physical examination of a pregnant patient.