Subchromosomal abnormalities can be positioned by the detection of copy number variation (CNV) using microarray comparative genomic hybridization (aCGH). aCGH has become a powerful tool in understanding the association between gene and genetic etiology in both research and clinical laboratories. Meanwhile as a new technique, controversies inevitably arose in its clinical application. As for the phenotype of CNV, little has been disclosed. For the clinicians, the difficulty in explanation of the CNV to the patients is obvious, which makes many doctors refuse to use aCGH for clinical diagnosis. Customized arrays have been exploited to decrease the uncertainty and efforts to search for a balance between overloaded information and insufficient information have been made. The purpose of this review is to discuss the current limitations and difficulties in application of aCGH in prenatal diagnosis and its application prospect from the point of a clinician.