First‐trimester maternal abdominal subcutaneous and perirenal fat thickness and early identification of gestational diabetes: A prospective cohort study

OBJECTIVE: To evaluate whether first-trimester abdominal subcutaneous fat thickness (ASFT) and renal fat thickness (RFT) provide incremental value for early identification of gestational diabetes mellitus (GDM) and their association with obstetric complications. METHODS: weeks) at the Division of Obstetrics and Gynecology, University of Pisa, Italy (2019-2020). ASFT and RFT were measured by transabdominal ultrasound. Fasting glycemia, pre-gestational body mass index (BMI), and weight gain were recorded. GDM was diagnosed by standard oral glucose tolerance test. Associations with GDM were evaluated using univariate and multivariable logistic regression analyses. Predictive performance was assessed using receiver operating characteristic (ROC) curves and model comparison. Obstetric complications were prospectively documented. RESULTS: GDM developed in 23.9% of the cohort. Women with GDM had higher BMI, first-trimester glycemia, upper and lower ASFT (all P < 0.001), and RFT (P < 0.01). After adjustment for BMI, ASFT-but not RFT-remained associated with GDM. A composite ASFT variable based on predefined cutoffs remained independently associated with GDM (odds ratio [OR] 2.31, 95% confidence interval [CI]: 1.17-4.72; P = 0.016). Inclusion of ASFT slightly improved model discrimination (area under the curve [AUC] 0.75 vs. 0.71). Using guideline-based risk factors alone, sensitivity for GDM detection was 85.9%, increasing to 95.3% after addition of ASFT, with reduced specificity. Neither ASFT nor RFT predicted obstetric complications. CONCLUSION: First-trimester ASFT measurement was independently associated with GDM risk and showed incremental predictive value beyond conventional clinical risk factors. These findings support further investigation of ultrasound markers of maternal adiposity for early risk assessment in pregnancy.