Maternal pre-pregnancy diet and prenatal depression: the mediating role of pre-pregnancy weight status and prenatal inflammation

Depression is a common prenatal psychological complication. We aimed to investigate if maternal pre-pregnancy diet can impact prenatal depressive symptoms and the mediating role of pre-pregnancy BMI and inflammation. We used data (N 1141) from the Alberta Pregnancy Outcomes and Nutrition cohort study. We calculated Mediterranean diet adherence (MED) and dietary inflammatory index (DII) scores using data from pre-pregnancy FFQ. In the third-trimester, we assessed depressive symptoms using Edinburgh Postpartum Depression Scale (EPDS) and inflammation through serum C-reactive protein (CRP) levels. BMI was calculated from self-reported pre-pregnancy weight. Race-stratified analyses (white and people of colour) were run. We observed no association between MED or DII tertiles and depressive symptoms. However, white participants in the MED tertile-3 had lower risk of depression (EPDS < 10) compared with tertile-1 (OR = 0<middle dot>56, 95 % CI, 0<middle dot>33, 0<middle dot>95). White individuals in MED tertile-3 had lower BMI (MD = -1<middle dot>08; 95 % CI, -1<middle dot>77, -0<middle dot>39) and CRP (MD = -0<middle dot>53; 95 % CI, -0<middle dot>95, -0<middle dot>11) than tertile-1, and those in DII tertile-2 (MD = 0<middle dot>44; 95 % CI, 0<middle dot>03, 0<middle dot>84) and tertile-3 (MD = 0<middle dot>42; 95 % CI, 0<middle dot>01, 0<middle dot>83) had higher CRP than tertile-1. Among people of colour, neither MED nor DII was associated with BMI or CRP, but BMI was negatively associated with depressive symptoms (beta = -0<middle dot>25, 95 % CI, -0<middle dot>43, -0<middle dot>06). We found no association between diet and depressive symptoms through BMI or CRP, in either race. Pre-pregnancy diet might affect the risk of prenatal depression in a race-specific way. Further research is required to explore the racial differences in the association between maternal diet and prenatal depressive symptoms/depression risk.