Herbs, I'm tempted to suggest you have a small do with closest nursery friends (as MI says, the nursery will be able to tell you who his closest friends are and hand out invitations), then separately you can dress up your next NCT get-together as a birthday event (presumably you meet at soft-play or similar...). Under no circumstances invite 35 children to your house.
I got chatting to another colleague yesterday, as we pondered the non-appearance of pg co-worker's "early" baby, and she mentioned that her labour was "quite short". In fact, she woke up in the middle of the night (DP was away, and 1yo asleep upstairs) with the dawning realisation that the baby's head was droppping, ran downstairs to phone 999, and actually had to drop the phone so she had her hands free to catch the baby before resuming the conversation with the operator.
She did say it was pretty scary (understatement!).
As for me, DS and DD2 were easy peasy, but small-for-dates DD1 was induced early. She didn't like the idea, and I ended up with an EMCS under GA. I remember the midwife and DH staring at each other, then she pressed a buzzer, and there was the sound of many running feet......Just like BD I simply closed my eyes and mentally checked out of the whole process.