This doctoral study examines the impact of polyunsaturated fatty acids (PUFAs) from black cumin, olive and flaxseed oil on metabolism and oxidant/antioxidant balance during pregnancies complicated by diabetes.The study reveals significant metabolic and redox imbalances during gestational diabetes, and highlights the immunosuppressive properties of flaxseed oil, rich in n-3 PUFAs, in contrast to the immunostimulatory effect of nigella oil, rich in n-6 PUFAs, on T-cell proliferation and cytokine secretion. The results underline the importance of PUFAs in improving oxidant/antioxidant status, suggesting their beneficial role in the management of gestational diabetes.