This is a very common concern when planning a wedding. Some people just prefer not to have young children at their event for one reason or another. Personally, I don’t see a problem with people bringing their children to the ceremony itself. After all, it should be a family oriented event. You are forming a new family when you get married. Even if a baby cries during your wedding, it will be the child of a close friend or relative. Is that really so bad? Chances are they will walk the child out of the church if something like that happens. In the end though, it is your decision to make.
I do completely understand not wanting children at your reception. Depending on the type of reception you are planning, it may be inappropriate for children to be there. Maybe you can’t afford it. Maybe the reception area is limited in seating. Maybe you just don’t particularly like kids. Everyone has their reasons.
You need not worry about other people’s feelings too much. In most cases, you are over thinking the concept. People understand. It is your wedding and your decision to make. Those people who get snippy about it are the type of people who get that way over everything. You certainly should not worry about pleasing them. No matter what you do, they will find something to complain about.
I also don’t see a problem with inviting young immediate family members or making exceptions in some cases. Again, you might think that it is unfair, but it is not. It is your party. You can invite anyone you want to for whatever reason. Your guests should be mature enough to respect that decision regardless.
How to let them know that you do not want children:
The easiest and classiest way to do this is to phrase your wedding invitations properly. You could say something like “Adult Only Reception and Cocktails to immediately follow the wedding ceremony.” People will notice the adult only part that you mention. To anyone with children, that is a very eye-catching phrase.
Some people might question you about the meaning. Just let them know that you have decided that it wasn’t going to be practical to invite children to the party. You do not need to explain it beyond that no matter who the person is. You should still feel completely at ease inviting immediate family members that are young though. There is nothing wrong with that and you certainly should not feel weird about it.
Remember this is your wedding day. It is your decision to make. If you are really torn about the idea, ask your parents about it. They will concur. It is your decision and you should not feel weird about it.