gravida I vs primigravida

gravida I and primigravida both are nouns.

Word	Noun	Adjective	Verb	Adverb
gravida I	Yes	No	No	No
primigravida	Yes	No	No	No

As nouns, gravida I and primigravida are synonyms defined as:

gravida I and primigravida: (obstetrics) a woman who is pregnant for the first time

gravida I (noun)	primigravida (noun)
(obstetrics) a woman who is pregnant for the first time	(obstetrics) a woman who is pregnant for the first time