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Screening for trisomies by cell‐free DNA testing of maternal blood: consequences of a failed result

First, to report the distribution of the fetal fraction of cell‐free (cf) DNA and the rate of a failed cfDNA test result in trisomies 21, 18 and 13, by comparison with pregnancies unaffected by these trisomies, second, to examine the possible effects of maternal and fetal characteristics on the fetal fraction, and third, to consider the options for further management of pregnancies with a failed result.