gestational age vs fetal age

gestational age and fetal age both are nouns.

Word	Noun	Adjective	Verb	Adverb
gestational age	Yes	No	No	No
fetal age	Yes	No	No	No

As nouns, gestational age and fetal age are synonyms defined as:

gestational age and fetal age: the age of an embryo counting from the time of fertilization

Other synonyms of gestational age include fertilization age.

gestational age (noun)	fetal age (noun)
the age of an embryo counting from the time of fertilization	the age of an embryo counting from the time of fertilization