obstetrics vs foetology

obstetrics and foetology both are nouns.

Word	Noun	Adjective	Verb	Adverb
obstetrics	Yes	No	No	No
foetology	Yes	No	No	No

As nouns, foetology is a hyponym of obstetrics; that is, foetology is a word with a more specific, narrower meaning than obstetrics:

obstetrics: the branch of medicine dealing with childbirth and care of the mother
foetology: the branch of medicine concerned with the fetus in the uterus

Other hyponyms of obstetrics include fetology, perinatology.

obstetrics (noun)	foetology (noun)
the branch of medicine dealing with childbirth and care of the mother	the branch of medicine concerned with the fetus in the uterus