I know that I was pregnant back in the dark ages (the 80s), but I was extremely active, doing hard, high impact aerobics through both of my pregnancies. The first one, I managed to do that through 8 months, but after that, I decided to walk and swim. Second pregnancy, I was super fit and super skinny. One day we decided to go for a family bike ride and I stopped short because I was worried that DS #1 was falling out of his baby seat on the back of DH's bike. The down tube shifters went into my stomach, hurting like hell, but I didn't really think of it. I had a bruise, though. Five days later, I went into premature labor, at 30 weeks. I had to endure 6 weeks of house arrest and my mom had to come and stay with us for 4 weeks. It was awful.
Was it worth it? No. I am sure my balance was off, despite my fitness, and that little wobble that caused the shifter to jab my belly would not have happened without my center of gravity being different from the pregnancy.
We often joke this is why DS #2 became a racer, but it was a very tense 6 weeks, that got me so agitated that I actually threw a plate across the family room at DH because I was so frustrated from having to stay in the house.
2015 Trek Silque SSL
Specialized Oura
2011 Guru Praemio
Specialized Oura
2017 Specialized Ariel Sport