TNF and gestational diabetes: The most commonly assessed cytokines were IL-6 (eight articles, higher or similar levels in GDM compared to non-GDM), TNF-α (seven articles, mostly higher or similar levels in GDM compared to non-GDM), IL-10 (six articles, mostly no difference between GDM and non-GDM), IL-2 (three articles, mostly no difference between GDM and non-GDM), and IFN-γ (three articles with contradictory results).