It is a tricky situation to try to have people only come to your wedding as couples and leave the kids behind with a sitter. There is no real easy or courteous way to say “leave the kids at home” without sounding like someone who hates kids. That being said, there are some ways that you could suggest to your guests that you intend for your wedding to be only for the adults in the household.
The first thing that you could do is write the invitation to the mother and father of the child, but leave the child’s name off. This is a nice way of saying that you would love to see mom and dad without clearly saying leave the kid behind. You could reinforce this with a line about how much you and your future spouse look forward to having the two of them at the wedding.
One of the best ways, however, to go about not inviting kids to a wedding ceremony is to pass the word through family and friends. Just suggesting things like the fact that alcohol will be served at the reception and dancing will be encouraged could cause some people to look for a babysitter. The best thing you can do is send the message through other people so it is not attached to you.