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 body mass index (BMI) and inflammation. We used data (N=1141) from the Alberta Pregnancy Outcomes and Nutrition (APrON) cohort study. We calculated Mediterranean diet adherence (MED) and dietary inflammatory index (DII) scores using data from pre-pregnancy food frequency questionnaire (FFQ). In the 3rd-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 color) 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 to tertile-1 (OR=0.56, 95% CI, 0.33, 0.95). White individuals in MED tertile-3 had lower BMI (MD=-1.08; 95%CI,-1.77,-0.39), and CRP (MD=-0.53; 95%CI,-0.95,-0.11) than tertile-1, and those in DII tertile-2 (MD=0.44;95%CI, 0.03, 0.84) and tertile-3 (MD=0.42; 95%CI, 0.01, 0.83) had higher CRP than tertile-1. Among people of color, neither MED nor DII were associated with BMI or CRP, but BMI was negatively associated with depressive symptoms (β=-0.25, 95%CI,-0.43,-0.06). 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.