Mixed Milk Feeding Patterns and Growth Outcomes During the First Year of Life in Asian Infants: Application of Predefined Feeding Clusters to Test Associations

Background: Varying definitions have been used to categorize mixed milk feeding (MMF) patterns in studies focused on feeding and infant growth, posing a challenge when making comparisons and interpretations. Furthermore, MMF encompasses vastly heterogeneous and evolving feeding behaviors that are difficult to standardize longitudinally. Objectives: We previously described a new approach for describing MMF patterns across the first year, using a multivariate clustering algorithm. In the current article, we aimed to describe the associated infant growth patterns across these identified feeding clusters in an Asian clinical study (N = 539). Methods: Using a linear mixed-effects model that included infant covariates, we estimated the associations between the different feeding clusters and longitudinal growth outcomes, including weight, length and BMI-for-age z-scores. Results: The cluster division explained a statistically significant amount of variation in growth trajectories, over and above the variation explained by included covariates. Differences in weight and length trajectories were observed between the clusters; the more breastfeeding that was included in a cluster, the closer the growth pattern resembled that of the breastfed reference group. No distinct differences in BMI trajectories were apparent within the first year of life. Mean weight-for-age z-scores per cluster all fell within ±0.5 SD of the WHO standard, indicative for adequate growth. Conclusions: The results of this study suggest that our previously defined milk feeding clusters can discriminate growth trajectories between the different feeding groups in the studied population. This confirms that our proposed approach has the potential to bring more precision to future studies examining associations between milk feeding patterns and growth (and potentially other health) outcomes in the first year of life across different populations. Conclusions on a causal effect of feeding characteristics should be made with caution because of the observational and exploratory nature of the analysis.This trial was registered at clinicaltrials.gov as NCT01609634.