Those whose babies have to get an NG tube

I brought my daughter in today to see another GI specialist who was able to get a feeding speciaist - OT to see her.  She's having feeding issues - she can't suck properly and this past week and half, she' eating 15 oz.  I was told if she doesn't gain weight by Monday, she will most likely have to get an NG tube as she hasn't gained any weight in a week.  She can't suck properly and I think she's having the beginning stages of bottle aversion - which her doctors have yet acknowledged b/c they haven't seen her in action yet...it happens half of the time. 

I've read that NG tubes causes oral and feeding problems...is that right?  I will have to do what is the best for her even if it means therapy, but just wanted to see if your babies experienced more feeding issues b/c of it.

- Cassie