If i was positive for chlamydia while pregnant, and got treated for it & blood test (for the re-test after a month) was negative, will they test me again at birth?

It is common in many centers to do a variety of screenings around the time of birth for STD's, hepatitis, and others. This accepts the reality that someone can pick up many of these infections at any time during pregnancy & recognition is the best way to assure both mom and baby receive proper treatment if needed. You may wish to clarify the issue with your doc.