Belfast District Birth record: 14th Sep 1916 at 15 Merrion Street. Sarah born to Mother Elizabeth Kane, A Spinner. No father recorded. Informant Mary O'Donnel, Occupier at 15 Merrion Street.
There was no father listed on the civil birth and the mother didn't list a maiden name. Perhaps her husband was deceased or away fighting in the War?
Hope that helps.
David