with child vs big

with child and big both are adjectives.

Word	Noun	Adjective	Verb	Adverb
with child	No	Yes	No	No
big	No	Yes	No	Yes

As adjectives, with child and big are synonyms defined as:

Other synonyms of with child include enceinte, expectant, gravid, great, heavy, large.

with child (adjective)	big (adjective)
in an advanced stage of pregnancy	above average in size or number or quantity or magnitude or extent
	conspicuous in position or importance
	given or giving freely
	generous and understanding and tolerant
	marked by intense physical force
	significant
	prodigious
	serious or severe
	loud and firm
	(of animals) fully developed
	in an advanced stage of pregnancy
	feeling self-importance
	exhibiting self-importance