I also recommend “Exercising During Pregnancy” by Dr. Clapp. I have a 4.5 month old and ran up until the day I was induced. My doctor told me there wasn’t a lot of science behind the heart rate number and just to listen to my body and stay hydrated. If I got tired, I slowed down and if I just didn’t feel like running that day, I didn’t. I also road my bike on the trainer all the way through my pregnancy. I was too nervous about being on the roads and falling. And swimming was the easiest to keep up.
I found a lot of comfort in reading the blogs of others triathlon mom’s to be and triathlon mom’s during my pregnancy. There are a lot of women out there who have been in your shoes and there’s something reassuring about being able to communicate with these woman.
My husband was also worried about me exercising while pregnant so he also read Dr. Clapp’s book. Also, the book The Best Birth had very easy to read chapters for fathers.
And your energy really comes back in the second trimester so enjoy it!