What is associated with the lengthening of the umbilical cord during labor?

The lengthening of the umbilical cord during labor is primarily associated with complete placental separation. When the placenta separates fully from the uterine wall, the cord can stretch and lengthen as the fetal position shifts due to contractions. This phenomenon is part of the normal physiological changes that occur during the third stage of labor. The umbilical cord lengthening is often indicative of the placenta transitioning from its adherent state to being expelled from the uterus after the baby is born.

Other options may involve scenarios that can occur during labor but are not directly related to the stretching of the umbilical cord. Decreased fetal movement, increased maternal pain, and loss of fetal heart rate might signify other conditions or complications but do not causally link to the specific physiological process of cord lengthening associated with placental separation.