Data on weight and length (BMI) during the first year were collected during the YHC routine visits where children are invited to at 1, 2, 3, 4, 6, 7.5, 9, and 11 months of age. These data were obtained from the YHC registry. During these visits, height was measured to the nearest millimeter with a
Leicester portable height measure (Seca, Hamburg, Germany). Weight was measured to the nearest 100 g with a calibrated Marsden M-4102 scale (Oxfordshire, UK) [36 (
link)]. From these data, BMI was calculated as weight in kilograms divided by the square of height in meters. For deriving BMI trajectories, non-standardized BMI values were used. At 5–6 years of age, data on child’s weight and height (for BMI) were obtained from the YHC registry (
n = 1235) or the ABCD health examinations (
n = 1868). The examinations were conducted by trained research assistants according to a standard protocol [33 (
link)]. Age- and sex- specific BMI standard deviation (SD) scores were derived according to the WHO growth standards [42 (
link)] using the Growth Analyzer Software, version 4.0 (Growth Analyzer BV). Overweight (including obesity) was defined as > + 1SD above the median of the WHO growth standards.
Sirkka O., Hof M.H., Vrijkotte T., Abrahamse-Berkeveld M., Halberstadt J., Seidell J.C, & Olthof M.R. (2021). Feeding patterns and BMI trajectories during infancy: a multi-ethnic, prospective birth cohort. BMC Pediatrics, 21, 34.