First, based on findings of previous observational studies, it is believed that investigated TNF-α, IL-6, IL-10 and ADIPOQ polymorphisms may alter transcription activity of TNF-α, IL-6, IL-10 and ADIPOQ, and this is also the primary reason why these polymorphisms have been repeatedly analyzed with regard to the risk of different types of diseases including GDM [15–17]. This evidence concerns the gene TNF and gestational diabetes.