OBJECTIVE: To explore the impact of in vitro cell subculture on prenatal diagnostic sample results and compare the efficacy of conventional karyotyping and chromosomal microarray analysis (CMA) in detecting chromosome mosaicism. METHODS: We conducted a retrospective analysis of G-banding karyotyping and CMA data from 2007 amniocentesis cases to investigate chromosome mosaicism. RESULTS: Chromosome mosaicism was detected in 1.49% of cases (30/2007). Sex chromosome mosaicism was the most common form of mosaicism. Among the 30 mosaicisms, 18 results were consistent between the two methods. In four cases, CMA indicated mosaicism but the karyotypes were normal. In eight cases, CMA was normal while the karyotypes suggested mosaicism. CONCLUSIONS: CMA and karyotyping complement each other in prenatal genetic diagnosis. Combining both methods enhances detection accuracy, particularly in cases of chromosomal mosaicism, which may be missed after the subculture of adherent cells in karyotype analysis.