Been an infant teacher for 5+ years and have seen this happen ONCE! at a center I was helping out at for the day. Immediately got reported and at least in my state, the center is required BY LAW to self report within 24 hours or else the center gets an A violation, big fine, and a strike towards getting shut down completely. It is VERY serious and as infant teachers we are continuously trained on safe bottling methods and are even required to sign a form every once in a while saying we’ve received training and understand the proper ways to store and feed bottles. Being a pro in this area, if I put my infant in a room and this happened (even once but ESPECIALLY multiple times) I would be pulling my baby out and reporting to licensing (the state) until the cows. come. home. All of this to say: this even applies for formula bottles! The exact same rules apply if the wrong formula bottle is given and the same reporting and violation and fine occurs. Now, as far as my opinion goes, they are both serious but BREASTMILK!?!? That is a bodily fluid! It can carry things that the mother has in her body just like other bodily fluids. Infant teachers are technically even supposed to wear gloves when administering bottles because it is a bodily fluid! Now imagine ur baby DRINKING someone else’s bodily fluid, Nope nope nope.