Effects of the Energy-Adjusted Dietary Inflammation Index During Pregnancy on Prenatal Depression: The Mediating Effect of Sleep Quality

(1) Background: Prenatal depression is prevalent and can adversely affect maternal and infant health. This study aimed to analyze the relationship between the energy-adjusted dietary inflammatory index (E-DII) and prenatal depression, as well as to explore the mediating effect of sleep quality. (2) Methods: In this cross-sectional study, a total of 749 pregnant women were enrolled. The E-DII scores were evaluated using semi-quantitative Food Frequency Questionnaires (FFQ); the Edinburgh Postpartum Depression Scale (EPDS) was used to measure depression levels; and the Pittsburgh Sleep Quality Index (PSQI) to evaluate the sleep quality of pregnant women. Binary logistic regression analysis was employed to analyze the relationships of E-DII with prenatal depression, of E-DII with sleep quality, and of sleep quality with prenatal depression. The bootstrap approach was employed to investigate the mediating effect of sleep quality. (3) Results: Findings indicated that a higher E-DII score was significantly associated with an increased risk of prenatal depression compared to the lowest score, and this association still existed after adjusting for sleep quality. In addition, the lowest E-DII score was also associated with a lower risk of poor sleep quality. Sleep quality played a partial mediating role in the association between E-DII and prenatal depression, and the proportion of the mediation effect relative to the total effect was 34.30%. (4) Conclusions: Sleep quality partially mediated the association between E-DII and prenatal depression. Close monitoring and proactive improvement of sleep quality among pregnant women following a pro-inflammatory diet may help reduce the risk of developing prenatal depression.