Population-specific genetic variation patterns could reshape personalized medicine approaches, particularly as genomic screening expands globally. Most genetic databases reflect Western populations, creating blind spots for other ethnicities that may carry distinct beneficial or harmful DNA variations. A comprehensive genetic analysis of over 46,000 Japanese pregnant women has mapped maternal copy number variations—sections of DNA that are duplicated or deleted—revealing population-specific patterns that differ from Western genetic databases. Using advanced sequencing technology originally designed for fetal chromosome screening, researchers identified genetic duplications in 6.3% of participants, with the most common variant occurring in 2.67% of women on chromosome 8. The study established rigorous detection thresholds requiring DNA segments of at least 0.8 megabases to ensure 100% accuracy in identifying genuine genetic variations versus technical artifacts. Cross-referencing with existing databases showed strong alignment with Japanese-specific genetic repositories but notable differences from global databases dominated by European ancestry populations. This research represents the largest systematic survey of maternal genetic variations in an Asian population, filling critical gaps in genetic medicine. The findings underscore how population ancestry influences genetic architecture, with implications for disease risk assessment, drug metabolism predictions, and reproductive counseling. While most detected variations appear benign, the population-specific frequency patterns suggest that genetic risk models developed primarily from Western cohorts may inadequately serve Asian populations. The work establishes essential baseline data for precision medicine initiatives targeting Japanese and potentially broader East Asian populations, highlighting the necessity of diverse genetic databases for equitable healthcare advancement.