I wrote this for my wedding and reception because our venue was an old location with many antiques and the reception was in the evening. People seemed to respond well to this 
maybe it'll help any of you with having to word "no children please"........
"We want you to know that we absolutely love children and plan to have some of our own one day. However, unless you are a part of the wedding party or the young "Johnson clan," we ask that you please find a babysitter for this event.
If your child or children are under 13 years of age a babysitter is appropriate. If they are 13 or over they are not required to come; we would love to have them, but they do have a choice whether or not they would like to.
If you are a nursing mother and cannot leave him/her alone with someone else because of that, we do have a room for you to go nurse and such
The reason for the restriction is that this is a formal event at a fairly aged venue and that means a good bit of antiques and old furniture at almost every turn. We love your children and we love you, but maybe take this opportunity to have a night of just the two of you on a date, in a romantic setting, with candle light, dinner, and dancing the night away remembering why you are married in the first place 
"