lying-in vs birth

lying-in and birth both are nouns.

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

As nouns, birth is a hypernym of lying-in; that is, 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
birth: the process of giving birth

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

lying-in (noun)	birth (noun)
concluding state of pregnancy; from the onset of contractions to the birth of a child	the event of being born
	a baby born; an offspring
	the process of giving birth
	the kinship relation of an offspring to the parents
	the time when something begins (especially life)

lying-in (verb)	birth (verb)
	cause to be born