It's both natural and grammatical. Option: Happy Birthday Number Three
New words, one handy idiom, and a 2-minute quiz — delivered to your inbox to keep your streak alive.
tinanam0102Suppose she was one year old. Do you say: "Happy first birthday" too?Yes you can
tinanam0102What is "Number Three"?Birthday number one is your first birthday
Anonymousis it also correct to use a phrase on her 2nd year birthday?Almost correct. Leave out 'year'.