My wife and I also have an adult-only party, and we do our best to be sure everyone understands that. I will admit feeling a bit awkward reminding some new folks that it is not a child-safe party, but it is everyone's interest ( I think) to make it as clear as possible on the invitations and in replies following RSVPs. There is alcohol, some gory props, and some fragile props that I want left alone. Luckily our friends have learned over the years to expect and respect our decision, and I think more than anything, I would feel more awkward if I knew my friends went to great lengths to get babysitters, etc. and then someone else drags their kid along with them. Having said that, we do let folks bring their <1 year olds. They generally leave early and are less likely to impact the party. Anyway, just my 2 cents.