childbearing vs giving birth

childbearing and giving birth both are nouns.

Word	Noun	Adjective	Verb	Adverb
childbearing	Yes	Yes	No	No
giving birth	Yes	No	No	No

As nouns, giving birth is a hypernym of childbearing; that is, giving birth is a word with a broader meaning than childbearing:

childbearing: the parturition process in human beings; having a baby; the process of giving birth to a child
giving birth: the process of giving birth

Other hypernyms of childbearing include birth, birthing, parturition.

childbearing (noun)	giving birth (noun)
the parturition process in human beings; having a baby; the process of giving birth to a child	the process of giving birth

childbearing (adjective)	giving birth (adjective)
relating to or suitable for childbirth