Which of the following is a typical sign of labor onset?

The onset of labor is marked by a series of physiological changes in the body, and one of the most definitive signs is regular contractions. These contractions are characterized by their increasing frequency, intensity, and consistency over time. Unlike Braxton Hicks contractions, which may occur in the later stages of pregnancy and do not lead to labor, true labor contractions occur at regular intervals and signify that the body is preparing for childbirth.

While increased energy levels, hospital admission, and light spotting with mild cramping can occur during pregnancy or at various points leading up to labor, they are not reliable indicators of labor onset. Increased energy levels, often referred to as the "nesting instinct," may happen in the days prior to labor but does not indicate that labor is imminent. Hospital admission typically occurs once labor is established or when there is a need for medical intervention. Light spotting and mild cramping can occur due to various reasons throughout pregnancy and do not alone signify the onset of labor.

Therefore, regular contractions are the hallmark sign that labor is beginning, firmly establishing labor's active phase and the need for appropriate care and preparation for delivery.