Prenatal (5)
'prenatal' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Another definition for fetal that I've seen is " about unborn child".)
(Other definitions for in utero that I've seen before include "Pre-natal position (Latin)" , "Embryonic" , "Where the foetus is" , "being developed" , "Before birth (Latin)" .)