I had trouble feeding mine in the hospital and the lactation nurses couldn't figure out why.
I was released on day 4 and day 5 had a Mother Baby Center nurse come to help. It turns out she wouldn't stay latched because of my pain Med's- she would get a sip and the pass out from the drugs.
The fact that the hospital lactation nurses didn't think to realize I had perc's and that would affect the process makes me think others she go through the same thing. :)