That must be hard for you. Honestly, if I didn't feel like I could keep it together I would contact the person throwing the party and just tell them why. Tell them that you are afraid to ruin a baby shower because you are very emotional right now. Also, if it is someone you care about I would send a gift. I would think that there wouldn't be any hard feelings because you honest about why you couldn't attend.
On the other hand, if they don't know about your loss and you don't want to tell them, I would make up some convienent excuse and simply not be able to make it at te last minute. Children get sick VERY fast ya know ( I know it is awful to use your kids to create fake ilnesses!! I get the bad mom of the year award for that idea!) I am just trying to help with some ideas if you are trying to get out of going.
True story- once we were in New Orleans on a weekend vacation and my DH 'accidentaly' signed us up for a time share presentation. They even got $20 out of him to ensure we would show up (I was shopping or this WOULD NOT have happened!). I went to the hotel where the presentation was and told them our dog was sick and we had to get home ASAP!! LOL!!! I made them give me my $20 back. The truth is that this particular dog is not all that smart and he eats just about anything small enough to swallow- this causes him to throw up alot. Once, he even threw up a chunk of concrete- NO JOKE!! I did recieve news that my dog had thrown up that morning, but it wasn't the emergency I made it out to be to the time share people
Just some ideas!! Let us know what you decide.