Can weight status in the first year of life predict well-being in the first years of school?

BACKGROUND: Early life represents a critical period for shaping long-term health outcomes, with early interventions playing a significant role in promoting well-being. This study aimed to investigate whether infant weight status could predict concerns of development and well-being in the first years of school using health nurse data. METHODS: Data from the Danish Child Health Database collaboration included 54 917 children and families who received home visits at 8-10 months and school examinations by health nurses during the children's first years of school. Weight status was measured using BMI z-scores and tested categorical, linear and using restricted cubic splines to explore predictive performance. Well-being was assessed by health nurses using seven indicators, including language skills, motor development, emotional well-being, and peer relationship problems. Model performance was evaluated through visualization of restricted cubic splines and by Area Under the Curve (AUC). RESULTS: Infant weight status at 8-10 months showed poor predictive performance (AUC < = 0.533) across all indicators of well-being in the first years of school. While certain weight categories-especially severe thinness, overweight, and obesity-were linked to specific concerns such as language skills and motor development, these associations had wide confidence intervals. CONCLUSION: Although infant weight status may indicate later health concerns, it was not a reliable predictor of health nurses' well-being concerns in the early school years. The findings demonstrated that predictive performance remained poor across several models, suggesting that infant weight alone may not capture the complexity of factors influencing later well-being as recorded by health nurses.