Subsequently, additional 61 articles were excluded for the following reasons: (1) one article on non-human model of GDM [42]; (2) two meta-analyses on association between TCF7L2 polymorphism and GDM; (3) 13 non case-control studies; (4) 34 studies unrelated to TCF7L2 gene and GDM; (5) five studies not focus on rs7903146 polymorphism; (6) four articles lacking genotype frequency data in the text or from corresponding authors [43–46]; (7) two abstracts [47–48] sharing -in part- the same participants with other articles [46, 49]. Here, TCF7L2 is linked to gestational diabetes.