Longitudinal Analyses of Diet Quality and Maternal Depressive Symptoms During Pregnancy: The Kuopio Birth Cohort Study

Background Depression and diet quality appear to be associated in the general pop-ulation. Nevertheless, little is known about their relationship among pregnant females.Objective The aims of this study were first, to investigate longitudinally whether or not diet quality is associated with depressive symptoms during pregnancy; second, to examine whether or not variation in diet quality during pregnancy predicts variation in depressive symptoms; and third, to explore how individual dietary components are associated with depressive symptoms.Design A longitudinal secondary analysis of the Kuopio Birth Cohort Study in eastern Finland was conducted. Data were collected from pregnant females during the first and third trimesters of pregnancy. Participants/setting The participants were 1,362 pregnant females who entered the study between 2012 and 2017.Main outcome measures Depressive symptoms, as measured with the Edinburgh Postnatal Depressive Scale during the first and third trimesters of pregnancy were used as continuous variables. Statistical analyses performed The main analyses consisted of linear mixed model analyses adjusted for potential confounders to longitudinally assess the association be-tween diet quality as measured by the Healthy Eating Index-2015, calculated using data from a food frequency questionnaire completed during the first trimester and third trimester, and depressive symptoms during the study period. An exploratory set of linear mixed models was also used to longitudinally assess the associations between selected individual food frequency questionnaire food groups and depressive symptoms.Results Descriptive analyses revealed that 12.3% of the participants had clinically relevant levels of depressive symptoms (ie, Edinburgh Postnatal Depressive Scale score >10) during either the first or third trimester. Longitudinal modeling suggested that depressive symptoms in pregnant females tend to remain stable throughout pregnancy. Females with a poorer quality diet already displayed higher levels of depressive symptoms during the first trimester of pregnancy (b =-.038 + .016; P = 0.022). Variation in diet quality did not predict variation in depressive symptoms over the course of pregnancy (b =-9.741 x 10-5 + .001; P = 0.869).Conclusions Females entering pregnancy with a poorer quality diet also displayed higher levels of depressive symptoms compared with females with a higher quality diet at the beginning of pregnancy, and this association remained constant throughout pregnancy. Further research is needed to assess the direction and the potential causality of the observed associations between diet quality and depressive symptoms. J Acad Nutr Diet. 2023;123(1):77-86.