Is pepto-bismol safe during pregnancy?

No: Peptobismol is not the best choice for diarrhea in pregnancy. It contains Aspirin like products which are generally not used in pregnancy except in certain conditions. Immodium is a better choice. If if you took a small amount of peptobismol already it is unlikely to cause problems.

Yes bu in moderation: Has bismuth so in small does should be ok unless you are at risk for premature labor than would avoid altogether.