What causes the cervix to stretch and sends nerve impulses to the hypothalamus, which signals the release of oxytocin from the posterior pituitary?
1) Oxytocin causes smooth muscle in the uterine wall to contract.
2) The placenta releases prostaglandins into the uterus, increasing the contractions.
3) Estrogen levels increase, leading to the onset of labor.
4) Progesterone levels decrease, allowing for contractions to occur.
