Topical tretinoin is a pregnancy class C medication. This means that using the medication is only recommended if the benefit of use outweighs the risk. For a cosmetic treatment like tretinoin, the safest course of action, therefore, is to stop using the medication if you are pregnant or trying to become pregnant.
But what if you recently discovered you are pregnant- do you need to worry about your baby’s exposure? Tretinoin has not actually been studied in pregnancy in humans for obvious reasons. The studies that have been done were all in rats. High doses of tretinoin were given orally to pregnant rats to see if it could cause birth defects, and the conclusion was that it can. But these studies don’t necessarily apply to the way tretinoin is used in people. The most important difference is that tretinoin is used topically, not ingested. And only very little tretinoin is absorbed into the bloodstream when the medication is applied to the skin. So even if you have used tretinoin while pregnant, most likely your baby was exposed to very little, if any, tretinoin. Stop using tretinoin as soon as you discover you are pregnant, and I would also recommend discussing any medications you are using with your Ob.