I understand adoption is a permanent chose and it really isn’t told that you can change your mind. If you are pregnant and wish to parent your child instead of choosing adoption that is your right.
Let’s talk legally for a moment. While you are pregnant you are still your unborn baby legal parent. At this time you have not signed any legal paperwork (outside of just working with so and so agency). Once you have your baby depending on your state you have a minimum of terminating your rights within 48-72 hours. Again it’s only a minimum and you do not have to do it if you do not want to. Let’s say that you still feel comfortable with adoption and still choose adoption there is a period of time where you can change your mind again. Depending on your state will determine how long you have and the process of doing so. In Georgia the law recently changed that now birth parents have 7 days instead of 10 days and it has to be a written letter.
Do not think that you do not have a choice to change your mind because that is your baby.