What is a key feature of the expanding family stage?

The key feature of the expanding family stage is that it starts when the first child is born. This stage marks a significant transition in family dynamics, as the arrival of the first child brings new responsibilities and changes in the household. During this stage, families typically focus on nurturing the child, establishing routines, and potentially expanding their support systems. This period is characterized by a shift in priorities, as the needs of the child become central to family life.

The other options do not accurately describe the expanding family stage. For instance, the period after all children leave home corresponds to the "empty nest" stage rather than the expanding stage. The marriage of parents marks the beginning of the family unit, but not specifically the expanding family stage itself. Additionally, low expenses are not characteristic of this stage, as families often experience increased costs associated with raising children, including healthcare, education, and childcare.