We are pleased that Mr Begleiter and Dr Finley concur with our opinions. It was not our intention to discourage obstetricians from offering cell-free DNA testing but to alert them that it is not diagnostic and should be used only for screening. We agree that the positive predictive value of this testing will be lower as screening for rare microdeletions is added. It is also important to note that most cell-free DNA testing currently is performed for patients with pregnancies with an increased risk of a trisomy. Thus, obstetricians should expect lower positive predictive values if they begin to offer this testing to low-risk pregnant patients. For this reason, we suggested that there should be disclosure of the positive predictive value to physicians and patients. Given the very high sensitivity and low false-positive rate when compared with other screening methods that are available, we would like to reiterate that we view the availability of screening for trisomies 21, 18, and 13 by testing cell-free DNA as a very positive development.