Biochemical-sonographic Correlations in First-trimester Screening for Foetal Aneuploidy: A Cross-sectional Study from Eastern India

Background: Aneuploidy screening constitutes an essential component of routine prenatal care worldwide, which is done by ultrasonography during the first trimester. Moreover, pregnancy-associated plasma protein-A (PAPP-A) and free β-human chorionic gonadotropin (β-hCG) reflect placental function, which serve as important biochemical markers for aneuploidy risk assessment. Aim: The present study investigated the correlation between maternal serum PAPP-A and free β-hCG levels with first-trimester ultrasound screening markers, i.e. nuchal translucency (NT) thickness and nasal bone (NB) for detecting fetal aneuploidy. Materials and Methods: This was a cross-sectional observational study, which enrolled 139 women with singleton pregnancies at 11–14 weeks of gestation. First-trimester ultrasonography was performed by an experienced doctor, and maternal serum PAPP-A and free β-hCG were also measured. Correlation investigation was done by Spearman’s correlation coefficient, while associations were done by Fisher’s exact test. Results: A significant positive correlation was observed between PAPP-A gestational age and maternal body mass index. Further, there were a strong negative correlation of NT thickness with PAPP-A multiples of the median (MoM) ( P < 0.001) and a strong positive correlation with β-hCG MoM ( P < 0.001). The fetal NB was absent in seven (5.0%) pregnancies, of which three were confirmed to have chromosomal abnormalities by noninvasive prenatal testing. Absent NB demonstrated 42.9% sensitivity and 100% specificity, while β-hCG levels were significantly higher in NB-negative pregnancies ( P < 0.01). Conclusions: The combined assessment of PAPP-A, free β-hCG, NT thickness, and fetal NB could improve the performance of first-trimester screening for fetal aneuploidy, enabling more accurate early prenatal risk stratification and facilitating timely clinical decision-making.