Association Between the Dietary Inflammatory Index and Depression in Mid-Pregnancy: Mediating Effect of Sleep Quality

The aim of this study was to assess the association between the Dietary Inflammatory Index (DII) and depression in mid-pregnancy and the mediating effect of sleep quality according to the Edinburgh Postnatal Depression Scale (EPDS).

This was a cross-sectional study conducted in 2017-2019 at a maternal and child health centre in Hunan Province. After applying the inclusion and exclusion criteria, 749 pregnant women were finally included in this study. A multifactorial logistic regression model was used to estimate the odds ratio (OR) and 95% confidence interval (95% CI) of the mid-pregnancy DII on mid-pregnancy depression. Restricted cubic spline plot regression was used to analyse the nonlinearity of the association between DII and depression. Mediation effects models were used to analyse the mediating role of sleep quality.

The average age of the 749 pregnant women was 29.42 ± 4.22 years. The mean mid-pregnancy DII was 0.21 ± 1.48 and the overall presenting rate of mid-pregnancy depression was 9.35%. In the final model adjusted for covariates such as maternal age, race, mid-pregnancy body mass index (BMI), occupation, literacy, and mean monthly income, the risk of depression in mid-pregnancy DII Q3 was 3.51 times higher than the mid-pregnancy DII Q4 [OR = 3.51, 95% CI = (1.45 to 8.53)]. A high DII in mid-pregnancy was a risk factor for depression in mid-pregnancy (p < 0.05). Restricted cubic spline plot regression analyses showed that the association between mid-pregnancy DII and depression could not be considered nonlinear. Sleep quality may play a mediating role between DII and depression in pregnant women in mid-pregnancy (25.26% of the total effect).

A high DII is a risk factor for mid-pregnancy depression. The Dietary Inflammatory Index can influence depression not only directly but also indirectly through the mediating effect of sleep quality on mid-pregnancy depression.