In Belgium, samples for prenatal genetic diagnosis are analyzed by Chromosomal Microarray Analysis (CMA). The main challenge herein lies in the interpretation of copy number variants (CNVs) for which knowledge about postnatal outcome is limited. All Belgian genetic centers have agreed on prenatal CNV classification, but ambiguous situations still occur. The goal of our research is to 1) investigate genotype-phenotype correlations using clinical data of children with prenatally registered non-benign CNVs; 2) narrow down the prenatal genotype-phenotype correlation of frequently found known pathogenic CNVs and 3) focus on outcome in children with other than benign CNVs and renal/urogenital anomalies on ultrasound. To secure our goals, we have created a Belgian database for registration of prenatal CMA data. In the first year of my PhD, I developed the framework of this database, guided the genetic centers in importing their data and presented our first results at international conferences. Next, I will start postnatal data collection of children with other than benign CNVs, determine renal function at the age of 1 year in case of a renal/urogenital ultrasound anomaly, and assess neurologic and psychomotor development at the age of 2-3 years. By ameliorating genotype–phenotype knowledge of prenatally registered CNVs, we will develop a strong scientific base for clinical decision-making in prenatal diagnosis. This work is a collaboration of all Belgian academic genetic centers.