Breastfeeding

So I found I'm expecting baby #2 a week ago and today I got my prenatal class from my doctor and suggested to wing off my son because it can cause pre labor contractions or something like that with baby #2. I feel so bad having to wing him off but I guess I have to soon, any recommendations ladies? He usually nurses for nap time and when we are ready for bed and a few times during the day. Than you :)