'intra-' originates from Latin, meaning 'within', combined with 'amniotic' which derives from Greek 'amnion' meaning 'fetal membrane' (the amniotic sac).

'amnion' (Greek) passed into Latin/medical Latin as 'amni-/'amnioticus' and entered English in medical usage as 'amniotic'; the Latin prefix 'intra-' (meaning 'within') combined with this root to form 'intra-amniotic' in modern medical English.

Initially the components literally meant 'within' + 'amnion (fetal membrane)'; the combined term has retained that literal meaning and is used specifically for processes or conditions occurring inside the amniotic sac.