Kenneth G. Wilson (1923–). The Columbia Guide to Standard American English. 1993.
birth (v.), birthing (n.)
These are found mainly in Southern and South Midland regional dialects. The verb, meaning to bear young, is still dialectal, but the noun appears to have become Standard, although some people may consider it still too special and will argue that it should continue to be labeled dialectal or as some of the jargon of modern midwifery and natural childbirth.
