Little white lie...

So, I had agreed to a boozy girls lunch next weekend but I’ve just found out were pregnant 🙌🏾😊. I’m only 4 weeks and I don’t feel comfortable telling the girls I’m pregnant yet nor do I really want to sit there sober while there all drunk and everyone knows how annoying drunk people are when you’re the sober one! Lol. Any suggestions on how I can get out of this one?