Ab work while TTC?

Heather • Mom to 19 month old, wife to the love of my life and best friend, and TTC #2!
I've been strength training for about 3 weeks now. I'm not training for competitions or anything, just wanna burn more calories at rest so I am building muscle. While on the crunch machine today, I was like, "can I do this while a baby is growing in there?" I'm 3 days into my TWW but I don't want to mess anything up.