gerund verbs

I want to explain my problems with following
sentences:

"It's about 3.30 p.m. when Salyaveth begins the radical mastoidectomy on Sor-u Pha's left ear. Drilling down behind the ear canal, he begins the delicate process of removing infection from the spongy mastoid bone just millimetres below the brain. An hour later, he piggybacks the boy out to his anxiously waiting mother."

If I place the word 'waiting' after the word
'mother' (......anxiously waiting mother), will it be wrong? Why? If it is not wrong, what kind of differences in meaning of that sentence will be appeared?