Is it safe to use retin-a topically while pregnant?

No. We really don't recommend it. Which is hard since most acne gets worse during pregnancy. Retin-a is similar to vitamin a and you can overdose on vitamin a during pregnancy which can injure your baby. You can do facial cleansers however.
Retin-A. No! Retin-A is a category c medication. This means animal studies show adverse fetal effects but no controlled human studies or no animal or human studies. Do not use Retin-A while pregnant.