Hey, I see you've already decided but I was having a similar predicament which is why I came on here to read if anyone else had already asked!
I am currently 12 weeks with my 2nd. With my first I ran until I was 35 weeks, racing the whole time but the longest was a half marathon at 18 weeks. I have been wanting to do an Olympic at the end of the summer but I've changed that to a Sprint next weekend instead. I just wasn't sure about the weather. I'm keeping an eye on the heat though - if it stays, I'll just stay home.
Good luck with the pregnancy and the training!
I honestly think that if I was further along and felt good, I might have raced. I know exercise doesn't cause miscarriage but I can't imagine how I'd feel if something doesn't work out with this pregnancy, I would always wonder if I did something by pushing myself too hard. I know my doctor said that I shouldn't wear a HR monitor but I normally do for training and today I was running an 11 minute mile and my heart rate was where it normally is when I'm running 8 min/miles during a race! I can't imagine that is good for anyone. I'm a bit sad that I'm missing the race (and had to come up with horrible excuses to the teammates that thought I'd be racing with them) but at least I know I'm doing the right thing for my body.
Yes, keep the heat in mind! I ran with a water bottle today and drank from it as often as I remembered to! Good luck with your pregnancy as well!