What does Hegar's sign indicate?

Hegar's sign indicates the softening of the lower uterine segment. This sign is observed during early pregnancy, typically around the 6th to 12th week of gestation. It reflects the physiological changes that occur in the uterus as it begins to accommodate the growing embryo. The softening can be felt during a pelvic exam and is due to increased blood flow and hormonal influences that act on the uterine tissues.

The other options refer to different aspects of pregnancy: softening of the cervix pertains to preparation for labor; fetal movement felt relates to the sensation of the fetus moving within the uterus, which generally occurs later in the pregnancy; and cervical effacement describes the thinning and shortening of the cervix that happens as the body prepares for delivery. While these terms are related to pregnancy and can indicate various stages or changes, Hegar's sign specifically pertains to the softening of the uterine segment, making it the correct choice in this context.