I would advise you to look in the county and state your relative lived as an adult, to see if there is some type of record about Proof of their birth.

I don't know how other states handle this situation, but my Mother was born at home in 1899 in McMillan Chickasaw Nation Indian Territory where there were no Record of Birth give to anyone. After WWII, mother realized she would need Proof of her Birth sometime in the future. Fortunately her Mother was still alive and my Grandmother gave an Affidavit and had it recorded IN THE COUNTY RECORDS where mother lived as an adult. They also knew a Doctor in OK who had once lived in McMillan, Marshall Co. OK & had moved to Ardmore, Carter Co. OK. They contacted him and ask him to give an Affidavit on when and where Mother had been born and this too was placed in record in the COUNTY AND STATE where Mother lived as an adult. I now have a Certifide Copy of this Poof of Birth. As far as I know, these were not recorded in Carter or Marshall Co. OK. I don't know requirements of other states, or if this type of Proof is in State RECORDS.

Nell