Which of the following is considered a sign of labor?

Regular contractions are an essential sign of labor because they indicate that the body is preparing for childbirth. During labor, the uterus contracts to help thin and open the cervix, allowing the baby to move through the birth canal. These contractions become increasingly consistent and stronger as labor progresses, making them a primary indicator that labor has begun.

Other options, while they may be experienced during pregnancy, are not definitive signs of labor. Increased appetite might occur in some individuals during pregnancy, but it does not point towards labor. Loss of energy can be a common feeling towards the end of pregnancy, known as "nesting" energy fluctuation, rather than a signal that labor is imminent. Nesting behaviors, chosen for preparing the home environment for the arrival of the baby, can happen at various stages in late pregnancy but are not a reliable sign of labor onset. Thus, the presence of regular contractions is a clear and critical sign that labor is underway.