The first stage of labor and birth occurs when you begin to feel persistent contractions. These contractions become stronger, more regular and more frequent over time. They cause the cervix to open (dilate) and soften as well as shorten and thin (efface) to allow your baby to move into the birth canal.
The  statement best defines childbirth is C. the process by which the uterus contracts to push the fetus out of the woman's body through the vagina.
What happens during childbirth biology?
The oxytocin causes the smooth muscle in the uterine wall to contract. At the same time, the placenta releases prostaglandins into the uterus, increasing the contractions. A positive feedback relay occurs between the uterus, hypothalamus, and the posterior pituitary to assure an adequate supply of oxytocin.
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