Association of Mediterranean Diet Scores with Psychological Distress in Pregnancy: The Japan Environment and Children’s Study

<b>Background/Objectives:</b> Perinatal mental disorders are important health issues that affect both mothers and their children. The Mediterranean diet (MD) is one of the most well-recognized healthy dietary patterns worldwide. Recent evidence suggests that MD may prevent or reduce the risk of perinatal mental disorders. This study investigated the association between MD adherence during pregnancy and psychological distress in a large cohort of Japanese births. <b>Methods:</b> Data were obtained from 80,271 pregnant women who participated in the Japan Environment and Children's Study. Adherence to the MD was assessed using three scoring methods: the Mediterranean Diet Score (MDS), relative Mediterranean Diet (rMED), and Mediterranean Diet Score for Pregnancy (PMDS). Psychological distress was defined as a score of ≥13 on the Kessler 6-item Psychological Distress Scale (K6). Modified Poisson regression models were used to estimate risk ratios (RRs) and 95% confidence intervals (CIs). Population attributable fractions (PAFs) were calculated to quantify the proportion of psychological distress attributable to low MD adherence. <b>Results:</b> The adjusted RR for psychological distress in the low PMDS group was 1.17 (95% CI: 1.07, 1.28) compared with the high PMDS group. The adjusted PAF for low PMDS was 10.43% (95% CI: 4.81, 16.06). No statistically significant associations were detected between psychological distress and the MDS or rMED scores. <b>Conclusions:</b> This study suggests that high adherence to MD based on the PMDS during pregnancy may reduce the risk of psychological distress in Japanese women. Therefore, promoting MD during pregnancy could be a potential strategy for preventing perinatal mental disorders.