Data from eight studies were included in the systematic review (GDM = 254, control = 309), and data from seven studies were included in the meta-analysis (GDM = 228, control = 286); the study by Sifnaios et al., 2019 was excluded from quantitative analysis because the authors only measured Tregs based on staining of peripheral T cells for the expression of the specific intracellular cytokine IL-10 instead of the predefined Treg markers determined in the methods. The gene discussed is IL10; the disease is gestational diabetes.