lying-in vs giving birth

lying-in and giving birth both are nouns.

Word	Noun	Adjective	Verb	Adverb
lying-in	Yes	No	No	No
giving birth	Yes	No	No	No

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

lying-in: concluding state of pregnancy; from the onset of contractions to the birth of a child
giving birth: the process of giving birth

Other hypernyms of lying-in include birth, birthing, parturition.

lying-in (noun)	giving birth (noun)
concluding state of pregnancy; from the onset of contractions to the birth of a child	the process of giving birth