i put on my invites something like this-
please come celebrate the new baby
Please come and join us for food and a big surprise (the scan was the surprise)
please don't bring a present, please come and have a great time.
Should you wish to bring something small, Aimee has included a registry for things that she needs.
I only put that because I know my friends and I know they bring lots of presents to parties.
no one came empty handed!!!!