Copy number variants (CNVs) associated with late-onset medical conditions are rare but important secondary findings in prenatal chromosomal microarray analysis (CMA). Searching a large cohort of prenatal CMA tests (N=16,238) at two tertiary centers, we show that such CNVs are identified in 0.1% of tests and do not culminate in termination of pregnancy. We developed a disclosure decision tool (DDT) which considers the severity, median age of onset, penetrance, understanding of genotype-phenotype correlation, and actionability of the finding, based on a five-parameter scoring system. The proposed decision tool may assist lab scientists and clinicians while reaching disclosure decisions. (By Dr Hagit Daum, https://jmg.bmj.com/content/early/2022/03/08/jmedgenet-2021-107890 )