Abstract
BACKGROUND: Liver health is critical in pregnancy due to this organ adapting to meet gestational metabolic demands. Although overall function typically remains normal, hormonal and metabolic shifts can alter hepatic structure and complicate assessment. Conventional liver tests and imaging (e.g., ultrasonography and biochemical markers) have limited ability to distinguish physiological changes from pathologies such as intrahepatic cholestasis of pregnancy, steatosis, or fibrosis. Ultrasound-derived fat fraction (UDFF) and automated point shear-wave elastography (Auto-pSWE) provide noninvasive, quantitative measures of hepatic fat and stiffness. These techniques are well established in nonpregnant populations, but their applicability for pregnancy-related liver changes remains underexplored. This descriptive pilot study aimed to establish trimester-specific reference values for UDFF and Auto-pSWE in healthy singleton pregnancies and to determine their correlations with clinical and biochemical parameters, thereby providing novel quantitative benchmarks for hepatic assessment during gestation. METHODS: Thirty normotensive women with singleton pregnancies underwent liver ultrasonography and biochemical evaluations during the first (11-13⁶⁄₇ weeks), second (20-24 weeks), and third (32-36 weeks) trimesters. Measurements included UDFF, liver stiffness (Young modulus in kilopascals) and shear-wave velocity (SWV; in meters per second), maternal anthropometric and serum biomarkers [alanine aminotransferase (ALT), total bile acids, and albumin]. Statistical analyses comprised Kruskal-Wallis tests for comparing trimesters and Spearman correlation coefficients for assessing associations between variables. RESULTS: Maternal body mass index (BMI) increased significantly across trimesters, from 20.68±1.79 to 23.77±1.82 kg/m(2) (P<0.001). UDFF values rose markedly, from 1.92%±0.30% in the first trimester to 4.58%±1.48% in the third trimester (P<0.001), corresponding to an approximate 139% increase. Liver stiffness parameters also increased significantly with gestational age: elasticity rose from 4.33±0.19 kPa to 5.80±1.43 kPa, while SWV increased from 1.26±0.03 to 1.45±0.05 m/s (both P values <0.001). Strong positive correlations were observed between UDFF and SWV (r=0.81), BMI (r=0.78), and ALT (r=0.77) (all P values <0.01), indicating an association between hepatic fat accumulation, tissue stiffness, and maternal metabolic status. Elasticity showed a significant association with total bile acids (P<0.05), indicating a potential link to hepatic functional changes. No significant correlations were found with albumin, total bilirubin, or coagulation indices. CONCLUSIONS: In this cohort, UDFF and liver stiffness increased across trimesters, reflecting physiological weight gain. These quantitative ultrasound biomarkers appear promising as noninvasive tools for monitoring early liver health, helping distinguish normal pregnancy-related hepatic changes from pathological conditions. The reference values reported in this paper may aid in improving prenatal liver assessment and guide timely interventions for optimizing maternal and fetal outcomes. However, these preliminary findings remain to be validated in larger multicenter cohorts with postpartum follow-up.