My mother cannot obtain birth certificate.

My mother was born in Puerto Rico in 1935, at the time of her birth it was common practice for the midwife to register the newborn child. The midwife did not give the registry my mother's name birth given name. (She did not like it.) She gave her another name (a male name) and that name is on her birth certificate. I tried to get her birth certificate with her birth name but it is impossible. She does not exist.