I know that both forms (1 year old and 1 year of age) exist, but when I tried to find some rule about usage, I couldn't (there are several forum threads about it, such as this and that, but they are not really helpful as they do not give ANY direction regarding the difference between the forms (if any)).
I need to use one* of these phrases in a formal context (drug leaflet). Currently the text says: "The medicine is not intended for babies under 1 year of age. For children 1 to 6 years old, the medicine is dispensed with a doctor's prescription only".
My questions are:
- Is there any preference to use either form, objectively or contextually?
- Is there a preference to use one or the other when stating an age range, i.e. would it be preferable to say "children 2-5 years old" over "children 2-5 years of age", or vice versa?
*I believe the same phrase should be used throughout the text.