Abstract
The evidence that fetal life and early infancy are "critical" or "sensitive" ages for later development of cardiometabolic disease is based on flawed methods for comparing different age periods. Moreover, most previous studies have limited their focus to weight gain, rather than growth in length/height or body mass index (weight (kg)/height (m)2). We undertook a secondary analysis of data from the Promotion of Breastfeeding Intervention Trial (1996-2010), a birth cohort study nested within a large cluster-randomized trial in the Republic of Belarus, that had repeated measurements of weight and length/height taken from birth to 11.5 years of age. We used mixed-effects linear models to analyze associations of changes in standardized weight, length/height, and body mass index during 5 age periods (conception to birth, birth to age 3 months, ages 3-12 months, ages 12 months-6.5 years, and ages 6.5-11.5 years) with fasting glucose, insulin, insulin resistance, β-cell function, and adiponectin at age 11.5 years. We observed strong associations between the metabolic markers and all 3 growth measures, with the largest magnitudes being observed during the latest age period (ages 6.5-11.5 years) and negligible associations during gestation and the first year of life. Later age periods appear more "sensitive" than earlier periods to the adverse metabolic association with rapid growth in childhood.