This study aimed to describe the association between the total antioxidant capacity, phytochemical index (PI), and dietary inflammatory index (DII) of the diet and ongoing pregnancy rate in infertile couples undergoing in vitro fertilization treatment. The study has a prospective cross-sectional design. Couples who met the inclusion criteria and underwent embryo transfer within the first 3 months after the interview were included. Total dietary antioxidant capacity, PI, and DII were calculated using a 1-year food frequency questionnaire. In addition, serum antioxidant and oxidant capacity, oxidative stress index, and C-reactive protein were assessed in venous blood. A total of 189 couples were included. Among these couples, the ongoing pregnancy rate was 32.3% (61/189). A significant difference was found between the DII scores of participants in the groups with and without ongoing pregnancy (P = .040 for males; P = .036 for females). A multivariate logistic regression analysis, adjusted for potential confounders, revealed no significant association between 1-year food frequency questionnaire derived dietary antioxidant capacity, DII, and ongoing pregnancy (P = .185 for females, P = .491 for males; P = .411 for females, P = .258 for males respectively). However, the PI was negatively associated with ongoing pregnancy (odds ratios: 0.169, 95% confidence intervals: 0.040-0.725, P = .027). The findings of the present study indicated an inverse association between the PI and ongoing pregnancy, underscoring the necessity for further research to investigate the impact of diet, particularly the PI and dietary inflammation, on reproductive outcomes.