Increased Cell-Free Fetal DNA Fraction in the First Trimester: A Sign of Abnormally Invasive Placenta? - Wertaschnigg, Dagmar; Lucovnik, Miha; Klieser, Eckhard; Huber-Katamay, Judith; Moertl, Manfred Georg (Ultraschall in der Medizin - European Journal of Ultrasound, 2018)