Aim: Based on the literature, MTHFR polymorphism is common among the general population and is controversial in terms of treatment, as it is poorly associated with pregnancy complications. In this study, we aimed to investigate the relationship between treatment and pregnancy outcomes in patients with MTHFR polymorphism.Methods: The data of 48 patients who were diagnosed with MTHFR C677T and A1298C polymorphism between June 2012 and April 2020 and followed up during their pregnancy were reviewed retrospectively. Demographic and clinical features of patients, pregnancy history, diagnosis, and perinatal complications were examined. Pre- and post-treatment clinical features of the patients were compared.Results: Comparison of pre- and post-treatment pregnancy data of the patients revealed that live birth rates were significantly higher (pre-treatment: 9.4% post-treatment: 68.7%, P=0.001) and abortion rates were significantly lower after treatment (pre-treatment: 81.2%, post-treatment: 32.1%, P=0.001). Pregnancy complications were observed in 9 (18.3%) patients. It was observed that among patients with MTHFR gene mutation, live birth rates increased by 24.12-fold and by 3.76-fold for each year of decrease in the age of conception following treatment. Conclusion: In pregnant women with MTHFR polymorphism, methionine-poor diet and medical treatment had a positive effect on pregnancy outcomes. It was also observed that among those with MTHFR gene polymorphism, young patients with MTHFR A1298C heterozygotes had the best treatment results.