Evaluation of the Diagnostic Performance of Prenatal Screening Markers for Down Syndrome in the Turkistan Region

Abstract

Highlights What are the main findings? Maternal age and fetal nuchal translucency (NT) showed the strongest associations with Down syndrome during first-trimester prenatal screening, whereas PAPP-A and free β-hCG did not retain independent statistical significance after multivariable adjustment. Incorporating nasal bone hypoplasia/aplasia into the prediction model improved the observed diagnostic performance, increasing the AUC from 0.855 to 0.903 while maintaining high specificity and demonstrating good calibration and internal validation. What are the implications of the main findings? The findings may inform further evaluation of prenatal risk assessment strategies in high-birth-rate regions, while external validation is required before potential clinical application. The findings provide evidence for optimizing prenatal screening services in high-birth-rate regions and support the future integration of region-specific prediction models into clinical decision-support systems and personalized prenatal care programs following external validation. Abstract Background: The Turkestan region is one of the regions with a high birth rate; therefore, analysis of the effectiveness of an early detection system for chromosomal abnormalities in this region is important for practical healthcare. Objective: To evaluate the diagnostic potential of first-trimester prenatal screening markers for identifying Down syndrome in the Turkestan region. Methods: A retrospective analytical study was conducted based on the analysis of medical records of pregnancies registered at perinatal centers in the Turkestan region between 2020 and 2025. The final analytical sample included 143 cases, comprising 71 pregnancies affected by Down syndrome and 72 randomly selected pregnancy cases included for comparative analysis. Maternal age, nuchal translucency (NT) thickness, pregnancy-associated plasma protein A (PAPP-A), free beta-human chorionic gonadotropin (free β-hCG), and fetal nasal bone hypoplasia/aplasia were assessed. Multivariable logistic regression and receiver operating characteristic (ROC) curve analysis were used. Results: In the multivariable analysis, maternal age (odds ratio [OR] = 1.16; p < 0.001) and NT (OR = 3.01; p = 0.001) showed statistically significant independent associations with Down syndrome. PAPP-A and free β-hCG did not demonstrate statistically significant independent associations in the multivariable model. The area under the ROC curve (AUC) was 0.855 for Model 1 and 0.903 for Model 2, which additionally included fetal nasal bone status. Conclusions: The exploratory models demonstrated good discriminatory performance within the present retrospective analytical sample. Maternal age and ultrasound markers showed the strongest associations with Down syndrome in the multivariable analysis. These models are not intended for direct clinical application at this stage and require external validation in independent and representative prenatal screening populations before their potential clinical utility can be assessed.