You can have a meet the baby party, but please do not call it a shower nor should you expect people to buy you anything. They very well may, but that is on them. Registry information should not be included on ANY party invitation for a party you are throwing yourself. Just plan on purchasing the majority of the things you need on your own.
You can all it a shower all you want although YOU should not host it yourselves. As long as someone else hosts it you can have an actual shower after the baby has arrived. I've hosted 2 of them and one is for the same reason you want it after the baby is born. And...you can register.
If you want to host the party yourself then it would be a "meet the baby party" only (not a shower) and you do not register. Most people would come with a gift but not what you normally would get at a regular shower. Mostly clothes and diapers.
Obviously there will be some things you will have to have before baby is born (carseat, a few onesies/sleepers, a few diapers, bottles if you don't BF, etc). You'll bring home a lot of things from the hospital (newborn diapers, receiving blanket, small diaper bag, thermometer, bulb syringe...anything that was used exclusively for your LO).
If someone is going to host an actual shower for you then you can call it a Meet the Baby Shower...but I wouldn't wait until the baby is too old. Also, wear the baby...that way people will most likely not ask to hold him/her.