"Do you want your child to be taken into care? Cause even if this is a joke someone will see this and report it to social services … deleted it now or you'll regret," one person wrote.
Others agreed, commenting that the mum's actions were "messed up" and harmful to her daughter.
"What especially p***es me off about this is you're practically shoving the glass in her face," one person commented.
"It's not a cute photo, she looks confused, it's really sad actually that you think this [is] acceptable."
"Don't let her drink that for God's sake!! What the hell," another said.
But the mother hit back at the criticism, writing that her daughter was "having some mouthfuls of beer" and not "shooting heroin".
"Clearly you've all never experienced being a mum cause if you did u would know that this isn't harmful to a baby," she wrote.
"My mum used to let me drink a little when I was young and would put whisky on my gums when I had sore teeth. I'd never put my baby in danger so all of you go to hell."
She also added that her daughter had "finished the end bit" of her beer and was still "here and happy and healthy".
People on Reddit also agreed with the commenters on Facebook, saying the drinking shown in the photo, which has since been deleted, could lead to dangerous habits later on.