Abstract Study question How do maternal age, BMI, and fetal fraction influence the accuracy of NIPT results, and what clinical implications arise from false-positive rates in specific populations? Summary answer Increased maternal age and obesity correlate with higher false-positive rates, particularly for Monosomy X, while lower fetal fraction significantly reduces the reliability of test results. What is known already Non-invasive prenatal testing (NIPT) based on next-generation sequencing (NGS) is a widely accepted method for detecting chromosomal aneuploidies such as Trisomy 21, Trisomy 18, and Monosomy X. Its high sensitivity and specificity are well-documented, but maternal factors like advanced age and elevated BMI may impact performance. Higher BMI often lowers fetal fraction, increasing false-positive results, while advanced maternal age raises the baseline aneuploidy risk. Although these associations are recognized, large-scale, longitudinal data with clinical outcomes remain scarce. This study examines the interplay of these factors using robust data from 38,160 cases to provide practical insights. Study design, size, duration This retrospective analysis included 38,160 NIPT results collected between 2016 and 2024 using consistent NGS technology. The study evaluated positive, confirmed positive, and false-positive rates stratified by maternal age (<35 vs. ≥35 years), BMI (normal, overweight, obese), and fetal fraction thresholds (<4%, ≥4%). Clinical outcomes of confirmed cases were reviewed to assess the direct impact of NIPT results on pregnancy management decisions. Participants/materials, setting, methods Samples from pregnant women were analyzed for common aneuploidies, including Trisomy 21, Trisomy 18, and Monosomy X, using NGS. Subgroup analyses were conducted based on maternal age, BMI, and fetal fraction. Clinical outcomes for confirmed positive cases were documented. Statistical analyses were performed to identify significant trends in false-positive and false-negative rates across the subgroups, providing insights into the influence of maternal demographic factors on test performance. Main results and the role of chance Among 38,160 NIPT results, the overall false-positive rate was 0.9%, with significant variability across subgroups. Women aged ≥35 years exhibited a higher false-positive rate for Trisomy 21 (1.5%) compared to those under 35 years (0.7%). Similarly, women with a BMI ≥30 showed an elevated false-positive rate for Monosomy X (2.2%) compared to women with normal BMI (0.8%). False-negative results were extremely rare (<0.03%), confirming the high sensitivity of NGS technology. Low fetal fraction (<4%) was identified as a critical factor contributing to false-positive results, particularly in obese women. Among all confirmed positive cases (n = 58), 100% resulted in pregnancy terminations following diagnostic confirmation, highlighting the clinical significance of NIPT results in guiding decision-making. Trisomy 18 demonstrated a 100% confirmation rate, while Monosomy X posed diagnostic challenges with the highest false-positive rate. These findings underscore the importance of integrating demographic factors into risk prediction algorithms to enhance test specificity. Personalized pre-test counseling and improvements in algorithmic sensitivity are recommended to address these disparities and optimize prenatal screening outcomes. Limitations, reasons for caution This study is retrospective and does not include follow-up on live births in negative cases or data on racial/ethnic differences. The findings are based on a single technology (NGS), and further multicenter prospective studies are needed to confirm the results and assess the generalizability to other populations and technologies. Wider implications of the findings Integrating demographic factors such as maternal age, BMI, and fetal fraction into NIPT algorithms could enhance diagnostic accuracy, reduce unnecessary interventions, and improve patient outcomes. Personalized counseling for high-risk groups is crucial to minimizing psychological stress and optimizing the clinical utility of prenatal screening. Trial registration number No
Read full abstract