No evidence show that teeth bleaching can be harmful to both you and your baby but there is no evidence that it’s safe too. Some manufacturers of whitening gel do not recommend their products during pregnancy because they don’t want to be liable if ever anything might happen.
If you really want to have a whiter teeth during pregnancy then the best thing to do is talk to your doctor and dentist for any recommendation they have for you. New technology offers laser for teeth whitening but since we are not 100% sure about it, maybe you can wait until you give birth. It’s better safe than sorry.
There’s a home remedy in whitening teeth, you can use baking soda. Mix it with water or your favorite toothpaste then brush your teeth. Do this only once in every two weeks.