 In this study, the investigators aim to develop non-invasive targeted molecular analysis using cell free fetal cff DNA and cff RNA for single-gene disorders, in pregnant women referred to the departments of Clinical Genetics of Maastricht University Medical Centre MUMC and Radboud University Medical Centre RUMC for conventional PND. The investigators will contribute to literature by confirming earlier published results, and by adding other single-gene disorders or mutations to the list of disorders for which the possibility of the use of cff DNA will be examined. 