An infant requires more constant care than a dying elderly. Parents are on rotation 24/7 for the first year. That's more than elderly get in hospice.
Moneywise it's $600k for a child. $400k from parents. $200k from the state for the free k-12 education.
Elderly on average have $200k in savings age 65-74 and spend $155k in medical costs their last 3 years.
Children are more expensive in money and direct labor.
The problem you describe as "temporary" implies that once your children are grown, they don't have further children that will use more resources.
A worker in a growing population can somehow support 4 children and 2 parents (6 dependents) yet supporting only 2 parents and no children (2 dependents) is a problem?
So no, it's not "temporary". It's a pyramid that eventually grows such that the foundation must crumble from the weight of everyone above.