A new study published in Prenatal Diagnosis evaluated the impact of offering cell free DNA cfDNA screening as a first tier test for trisomies 21 and 18. In this prospective study 1198 pregnant women undergoing conventional prenatal screening were offered cfDNA screening in the first trimester with clinical outcomes obtained on all pregnancies. It was found that the detection rate of trisomy 21 with standard screening was 83 with a false positive rate of 5.5 compared to 100 detection and 0 false positive rates for cfDNA screening. The fluorescence photobleaching recovery FPR of cfDNA screening for trisomy 18 and trisomy 13 was 0.09 for each. Further 2 of these women underwent an invasive diagnostic procedure based on screening or ultrasound findings without the cfDNA screening this rate could have been as high as 6.8 . Amongst the 640 women with negative cfDNA results and a nuchal translucency NT ultrasound only 3 had an NT greater or equal to 3.5mm one had a normal outcome and two lost their pregnancy before 20 weeks. From the results it was concluded that cfDNA screening has the potential to be a highly effective first tier screening approach leading to a significant reduction of invasive diagnostic procedures. It was stated that NT measurement has limited clinical utility in women with a negative cfDNA screening result.