Maternal obesity increases the risk of gestational diabetes mellitus (GDM) and is positively correlated with neonatal obesity increasing the risk of adiposity in both young and adult offspring. Maternal secreted factors from adipose tissue such as adipokines and inflammatory cytokines may regulate fetal growth. This study investigated associations between maternal adipokines and inflammatory markers at late gestation, and neonatal anthropometric characteristics in mothers with and without GDM. The study included 65 women with GDM and 65 pregnant women with normal glucose tolerance evaluated at the time of term elective Caesarean section. Adiponectin, leptin, resistin, adipsin, neutrophil gelatinase-associated lipocalin (NGAL), nerve growth factor (NGF), monocyte chemotactic protein-1 (MCP-1) and tumor necrosis factor-alpha (TNF-alpha) concentrations were measured in maternal serum by the multiplex immunoassay using Magpix technology. C-reactive protein (CRP) was measured with a particle-enhanced turbidimetric immunoassay and neonatal anthropometric variables were assessed. The association of birthweight with individual biomarkers was analyzed using multivariate logistic regression adjusted for maternal factors. Adiponectin, leptin, resistin, adipsin, NGAL and NGF were not significantly associated with higher birthweight. The maternal factors in association with higher birthweight observed in GDM were CRP, MCP-1 and TNF-alpha levels. Regression analysis showed that TNF-alpha was an independent risk factor for higher birthweight (p = 0.046). These results suggest an involvement of maternal inflammatory markers at late gestation and fetal growth in mothers with GDM, and that TNF-alpha could play a major role.