My DD was born at 36 weeks.. There were concerns about her sucking ability and size..

she was born screaming and when she did eventually get to Bf (10 hours old) she attached better then any of my other kids. A real trooper she was.. No breathing issues at all.. Only issue we had was low Blood sugars due to me having gestational Diabetes..

I have to add I had had 2 lots of steroids previous to delivery so this may have helped some what

good Luck to your sister..