Parturition is triggered by which hormone?

Parturition is the process of giving birth (childbirth). It is induced by a complex neuroendocrine mechanism. The process begins with signals originating from the fully developed fetus and the placenta, which induce mild uterine contractions known as the **fetal ejection reflex**. This reflex triggers the release of **oxytocin** from the maternal posterior pituitary gland. Oxytocin acts on the uterine muscles (myometrium), causing stronger contractions. These contractions, in turn, stimulate further secretion of oxytocin. The stimulatory reflex between the uterine contraction and oxytocin secretion continues, resulting in increasingly stronger contractions, which eventually leads to the expulsion of the baby out of the uterus through the birth canal.