Did your doctor know you were pregnant when they were prescribed for you? Many are safe to take. But now that you have already taken then, just tell your doctor what they were if they were not the one that prescribed them or you didn't know you were pregnant when they were prescribed.
Congrats on your baby! When are you due?
I would speculate that if you don't take the antibiotics, you would hurt your baby more. If you doubt your doctor, ask for another doctor.