Final answer:
The maternal characteristics of the first stage of active labor involve the thinning and dilation of the cervix. True labor refers to the regular contractions that become more frequent and powerful over time. These contractions are stimulated by the stretching of the myometrium and cervix by the fetus.
Step-by-step explanation:
The maternal characteristics of the first stage of active labor involve the thinning and dilation of the cervix. During this stage, the cervix expands to approximately 10 cm in diameter to allow for the baby and placenta to be expelled during birth. The myometrium and cervix are stretched by the fetus, which stimulates uterine contractions. These contractions, known as true labor, become more frequent and powerful over time.