Maternal and Child Diet Quality Trajectories and Their Determinants.

This study examined the trajectories of maternal and child diet quality in the first 5 years postpartum and their determinants. Data of 330 mother-child pairs from the Melbourne Infant Feeding, Activity and Nutrition Trial Programme were used. Maternal and child dietary data were collected using validated food frequency questionnaires, with maternal data collected when children were aged 4, 18, 42 and 60 months and child data at ages 18, 42 and 60 months. Maternal and child diet quality were calculated using the 2013 Dietary Guideline Index and the Dietary Guideline Index for Children and Adolescents, respectively. Group-based multi-trajectory modelling was conducted to examine multi-trajectory groups following distinct joint trajectories of maternal and child diet quality. Determinants of multi-trajectory groups were evaluated using logistic regression. Three distinct multi-trajectory groups of low (10.9%), moderate (57.6%) and high (31.5%) maternal and child diet quality were identified; high diet quality represented better adherence to dietary guidelines. Higher maternal prepregnancy BMI was associated with a higher relative risk of following the low (RRR 1.11; 95% CI: 1.02, 1.21) versus the high maternal and child diet quality multi-trajectory group. Breastfeeding for ≥ 6 months was associated with a lower relative risk (RRR 0.37; 95% CI: 0.15, 0.91) of following the low versus the high maternal and child diet quality multi-trajectory group. The longitudinal association between maternal and child diet quality suggests that interventions to improve maternal diet quality will likely benefit child diet quality. Interventions should target women with a high prepregnancy BMI and promote breastfeeding.