Labour

Labour is also known as parturition. This event typically begins with uterine contractions.
Uterine contraction occurs during the whole pregnancy, however, as close as it gets to the big moment, the contractions become stronger and more frequently.
The onset of labour includes hormonal and neural components. Everything start by the stretch of the cervix, which starts the release of the hormone oxytocin, from the posterior pituitary gland. The oxytocin stimulates the contraction, that will bring the baby downwards, stretching the cervix even more, repeating the cycle.