IL6 and hydrops fetalis: Three biomarkers were assessed across studies: Interleukin-6 (IL-6): 5 studies: BIOSTAT-CHF 2019 [18], ASCEND-HF 2021 [30], Chia 2021 [29], Berger 2024 [23], DAPA-HF 2025 [22]; High-sensitivity C-reactive protein (hs-CRP): 5 studies: Zhang 2023 [19], He 2023 [20], Zhu 2025 [21], Ferreira 2024 [27], Santas 2024 [25]; Neutrophil-to-lymphocyte ratio (NLR): 3 studies: Turfan 2014 [24], Curran 2021 [26], Davison 2022 [28].