If you find out you are pregnant don't worry about damage done to the baby. The rules are still the same fasting or not- the baby will be as well nourished or better nourished than you are. It's priority would be equal with your heart and brain no doubt. In fact creating the first cells of the life inside you by autolysis rather than from ingested food is a lot safe in my opinion than the haphazard way it is often done on less than perfect nutrition. I wish I'd been more savvy about this stuff before I had my kids.
And if/when you do find out you are pregnant and decide to end the fast just be tripley careful that you break your fast correctly, that will be the danger time for you both if you aren't careful.