Working out cramps

I have been trying to keep working out. I am not a super huge workout person who runs miles a day. But i do strength or cardio every other day or every day. I have been trying to keep it up but about 15 minutes in i get awful cramps. I have been careful not to do too much with my stomach. It just makes me so nervous that I’m scared to workout but i know that working out is good for me and the baby. This is baby #1. Is that normal? Am i safe to keep working out?