It depends on how early in life the test is done. I know that our pedi waited until my son was 24hrs old before he would do the tests. Even then he had the test repeated for accuracy. We were told that if it was done to early in life it can produce a faulse positive. I also have a cousin on my side of the family that is not affected by CAH who's daughter tested positive for CAH and was retested two more times and both were negative. The first test was done to soon after birth and they claim that was why the faulse positive.