birth pangs vs labor pains

birth pangs and labor pains both are nouns.

Word	Noun	Adjective	Verb	Adverb
birth pangs	Yes	No	No	No
labor pains	Yes	No	No	No

As nouns, birth pangs and labor pains are synonyms defined as:

birth pangs and labor pains: a regularly recurrent spasm of pain that is characteristic of childbirth

Other synonyms of birth pangs include labour pains.

birth pangs (noun)	labor pains (noun)
a regularly recurrent spasm of pain that is characteristic of childbirth	a regularly recurrent spasm of pain that is characteristic of childbirth