No, you do not capitalize "first birthday" in a sentence.
Your 10th birthday is your first two-digit birthday. In the same way, your 100th birthday is your first three-digit birthday.
It is unclear who the first person to celebrate their birthday was in the world. It is possible that the first man to celebrate their birthday was Adam, the first man created.
Tommy's First Birthday was created on 1991-08-11.
Diana Barry was the first to greet Anne on her birthday.
Mauras Birthday ist the first january
I think it is called The one with Emma's first birthday.
"Happy 1st Birthday"
Mauras Birthday ist the first january
That would be your 10th birthday of course !
the day he was born when was the first time your parents celebrated your birthday?
my birthday is on january 1 i feel like the first birthday ever