Harmonisation of Dietary Intake Data in Pregnant Women: Data from the Brazilian Maternal and Child Nutrition Consortium—BMCNC

Background/Objectives: This study describes the process of harmonising data from food consumption screeners (FCSs) and food frequency questionnaires (FFQs) in pregnant women, highlighting challenges and strategies. Methods: It is a methodological, descriptive study on the harmonisation of individual food intake data. The data were divided into two datasets: FCS and FFQ. FCS responses were categorised as “never/almost never”, “1–4 days per week”, and “≥5 days per week”. FFQ data were harmonised by deriving variables in grams per day. Outliers were identified using z-scores for total harmonised caloric intake exceeding ±2 standard deviations. The distribution and heterogeneity of the derived variables were assessed using multilevel models. Results: Data were drawn from 12 studies conducted in Brazil, part of the Brazilian Maternal and Child Nutrition Consortium (BMCNC). The sample included pregnant women aged 18 years or older, at any stage of pregnancy. The final harmonised datasets comprised eight studies (n = 5484) with FCS data and four studies (n = 1759) with FFQ data. Most food categories in the FCS dataset had comparable frequencies across studies, with differences observed for natural juices, soft drinks, and sweetened beverages. In the FFQ data, the largest variations in daily consumption were found for leafy vegetables, sweetened beverages, and soft drinks. Heterogeneity ranged from less than 0.01% for beans (FCS) to 15.5% for fruits and natural juices (FFQ). Conclusions: By enabling standardised analyses across diverse Brazilian populations, the harmonised BMCNC datasets provide a valuable resource for investigating nutritional inequities and supporting future research to improve maternal and child nutrition.