Research on the association between PAPP-A, free β-hCG and fetuses with estimated fetal weight below the 10th percentile in pregnant women at term

Background: Small for gestational age (SGA) is one of the most important conditions associated with the risk of perinatal mortality and morbidity. The levels of PAPP-A and free β-hCG in the first trimester can predict this adverse outcome. This study was conducted to investigate the role of PAPP-A and free β-hCG levels in predicting SGA. Objectives: To investigate PAPP-A and free β-hCG levels and evaluate the association with fetuses having an estimated fetal weight below the 10th percentile. Materials and methods: A cross-sectional descriptive study was conducted on 47 pregnant women with EFW < 10th and 94 pregnant women with EFW between 10th percentile and 90th percentile at Hue University of Medicine and Pharmacy Hospital from April 2023 to August 2024. Results: In the SGA group, the median MoM PAPP-A was significantly lower (0.59 vs 1.22, p < 0.001) and the MoM free β-hCG was significantly higher (1.47 vs 1.08, p = 0.046) than in the AGA group. At the cut-off MoM PAPP-A = 0.863, the sensitivity was 72.34%, specificity was 73.4% for predicting SGA. At the cut-off MoM free β-hCG = 1.281, the sensitivity was 63.83%, specificity was 60.64%. Low MoM PAPP-A (≤ 0.863) increases the risk of small for gestational age (SGA), with an odds ratio (OR) of 7.218 (95% CI: 3.289 - 15.842); similarly a high MoM free β-hCG (> 1.281) also increases the risk of SGA, with an OR of 2.889 (95% CI: 1.386 - 6.020). Conclusion: Low levels of PAPP-A and high levels of free β-hCG increase the chance of developing SGA; therefore, they are warning indicators for SGA.