how do you write "because it was her birthday" in italian?

Question

Perché era il suo compleanno.

is this correct

Answer 1

From yr correct sentence in Italian (perché era il suo compleanno) we can't know if it's referred to a man or to a woman.Retranslated into English it can be either "because it was his birthday" or "because it was her birthday".
If you want people understand it's referred to a female you should say / write:
"Perché per lei era il suo compleanno" or less literally
"Perché lei festeggiava il suo compleanno"

Answer 2

perché era il suo compleanno

Answer 3

perché era il suo compleanno-you got it.

Answer 4

That is correct.