Final answer:
Braxton Hicks contractions are a sign that labor may be beginning, and oxytocin is the hormone responsible for contractions during labor. Progesterone decreases at the end of pregnancy to reduce uterine contractility inhibition, aiding in labor initiation.
Step-by-step explanation:
The nurse will emphasize Braxton Hicks contractions as an indicator of the beginning of labor when teaching a first-time pregnant patient. These irregular contractions are sometimes referred to as "false labor" and can be a sign that the body is preparing for the actual labor process. True labor is distinguished by regular contractions that become more powerful and frequent over time. Furthermore, the hormone oxytocin is primarily responsible for the contractions during labor, which are stimulated when the fetus pushes on the cervix, sending a signal to release more oxytocin.
Before the baby and placenta are expelled, several physiological events occur. Stages of childbirth include cervical dilation, expulsion of the newborn, and afterbirth. A decrease in progesterone levels towards the last weeks of pregnancy helps initiate labor by decreasing inhibition of uterine contractility and thus allowing for cervical dilation.