Can my new employer fire me for necessary medical appointments due to pregnancy?

Based on your question, it appears as if you have already been hired.  If you have not been hired, you do not have to disclose that you are pregnant, and your employer cannot legally ask you if you are pregnant.  As far as whether they can fire you for visits related to your pregnancy, the answer is no.  They cannot fire you for that reason.  The Family Medical Leave Act ("FMLA") and the Americans with Disabilities Act ("ADA") prohibit such discrimination.  However, Indiana is an at-will employment state, so your employer could still fire you and give you a different reason for your termination, or no reason at all.  The burden would be on you to prove that your employer terminated you because of your pregnancy.  This can be very difficult to prove.  If you have specific questions about your situation, please feel free to contact me.