Generally, weddings are supposed to be a 'family event', and I think it slightly odd when people specify that children are not allowed..... usually people without any!
And, yes, like IndigoMoon pointed out, the best childcare usually for daytime-turning into nighttime, going through bedtime routine etc.... IS one of your own parents, or more than likely someone you trust who will also be at said wedding - therefore either one of you goes, or neither.
My cousin had a 'no kids' wedding, and my DH did not go in the end. In fact, he was so offended and thought it so peculiar that he was quite happy not to go.
It was also on Friday, so also expecting people to take the day off work,..... all rather selfish and self-centred if you ask me.
What is the reason anyway? Most parents would willingly take a noisy infant out of a church in the middle of a ceremony, or speeches, or anything requiring a bit of quiet, and by the time people are enjoying a bit of latenight dancing and indluging in drink, the kids have been taken back to bed, and these awful, selfish parents have left with them....
--- hhmmm.... seems I feel quite strongly about this! Oops.