I would say invite the people that see her regularly.

We had a pretty big party for Hannah's first birthday. I know she won't remember it but I will remember it for the rest of my life... so in essence the party was more for the adults than it was for Hannah lol. We had almost 30 people in our little house. there were about 6 children here and hannah really enjoyed them.

But.... many of those people were also invited because Brian's parents were coming in from Florida and they don't get to see this side of the family very often so it was more than just for a first birthday party.

If it weren't for that the list would have been cut down to just the people that see her most often.

Either way... don't stress yourself out about it. You will always remember her first birthday and you want it to be a pleasant memory.