Final answer:
The transition to parenthood within the family life cycle is known as the parenthood stage, where the couple starts raising their first child.
Step-by-step explanation:
The stage of family development in which the transition to parenthood is seen as a major event is known as the parenthood stage. This stage refers to a period in the family life cycle where a couple begins raising their first child. This time is marked by significant adjustments as the family adapts to the presence of a new member and the roles of the parents evolve. The parenthood stage follows the initial phase of marriage without children and precedes the stages where children grow and eventually become independent.