Fetuin-A Concentration in the Perinatal Period and Maternal BMI Dynamics During Pregnancy, Labor, and Early Postpartum: Is ΔBMI a Parameter Worth Considering?

<b>Background/Objectives</b>: Fetuin-A is a multifunctional glycoprotein involved in metabolic and inflammatory regulation. Although its role in insulin resistance, type 2 diabetes, and cardiovascular disease is well recognized, its relationship with pregnancy-related body mass changes remains unclear. This study aimed to explore associations between maternal BMI dynamics during and shortly after pregnancy and serum fetuin-A concentrations. <b>Methods:</b> Fifty-five healthy Caucasian women with term singleton pregnancies were enrolled. BMI was recorded at three time points: pre-pregnancy, before delivery, and 48 h postpartum. Based on ΔBMI (postpartum minus pre-pregnancy BMI), participants were divided into two groups: ΔBMI ≤ 1 kg/m² (<i>n</i> = 32) and ΔBMI > 1 kg/m² (<i>n</i> = 23). Serum fetuin-A levels were measured before delivery and postpartum using ELISA. Additional laboratory parameters and body composition were assessed postpartum via standard tests and bioelectrical impedance analysis (BIA). <b>Results:</b> No significant differences were found between groups in BMI at any single time point or in laboratory or BIA-derived parameters. However, all three BMI change indices (ΔBMI_gestational, ΔBMI_puerperal, and ΔBMI) differed significantly between groups. Fetuin-A concentrations did not differ significantly between groups. Importantly, fetuin-A levels decreased significantly after delivery in both groups, suggesting a potential role of the placenta in its regulation. A significant correlation was observed between pre-delivery fetuin-A and postpartum uric acid in Group ΔBMI > 1 kg/m² (<i>p</i> = 0.016), indicating a possible link in women with greater gestational weight gain. <b>Conclusions:</b> While fetuin-A was not directly associated with BMI changes, its peripartum dynamics and correlation with uric acid may reflect underlying metabolic-inflammation pathways. ΔBMI indices may offer a more individualized measure of weight dynamics in pregnancy research.