"youngest age" is correct and usable in written English and can be used to describe the lowest age in a range of ages.
For example, "At the youngest age, children are only 4 years old."
All devour two slices except the youngest, age 2.
At even the youngest age level, football is becoming a factory production line.
Most of these voters are in the two youngest age brackets 18-244 and 25-34).
Skinner's finding is even truer for children broadly than it is of the youngest age group.
In the youngest age groups coaches pitch, or pitching machines are used.
From the youngest age I had romantic delusional ideas about being jaded.
Even within the youngest age group 16-244), 47 per cent are in a stable relationship.
The ONS also pointed out that Muslims had the youngest age profile in 2001.
Even some of the youngest age groups are instructed by highly qualified coaches in Iceland.
Peck Peck Peck is an interactive storybook that won the hearts of the youngest age category.
Lower overall basal insulin requirements were found in the youngest (age ≤10) and oldest (age >60) groups.
