On the basis of fully developed / foetus and signals produced from placenta, contraction expulsion. Ejection of foetus are included and mild uterine contractions are induced.

This triggers release of oxytocin from the maternal pituitary oxytocin acts on the uterine muscle and causes stronger uterine contractions.

The combined effect occurring at a time of uterine contraction and oxytocin secretion continues. resulting on stronger contraction of the baby out of the uterus through the birth canal – parturition.