Relation between high weight at birth and obesity at first grade in a cohort of Chilean children

The purpose of this longitudinal study was to evaluate if macrosomic babies (>=8.8 lbs.) and/or big to gestational age (BGA) children developed obesity at first grade at Chilean public schools (at ~ 6 years old). A total of 119,070 children were identified and followed up using a cohort study. Demographic and anthropometric measures were collected and analyzed using chi square with bivariate analysis and logistic regression to determine odd ratios (OR) and relative risk. At birth, 18% were small for gestational age (SMA), 77, 8% were normal for gestational age, and only 3, 3% were big for gestational age. On the other hand, the prevalence of newborn < 5.5 lbs. was 4.6% while macrosomic babies >= 8.8 lbs., were 7.6%. At first grade, 6.7% were low weight, 20% overweight and 14.6% obese. In children >= 8.8 lbs., prevalence of anthropometric measures of birth and at first grade of school showed 24.1% and 21.7% of overweight and obesity, respectively. At their first grade of school,22.9% and 20% of children with high ponderal index at birth were overweight and obese, respectively. Additionally, 23.1% and 21.3% of BGA new born babies were overweight and obese, respectively at same grade of school. In contrast among new born < 5.5 lbs. only 14.6% and 11.1% were overweight and obese, respectively. Analysis using relative risk demonstrated that macrosomic babies were 1.55 (CI 1.48-1.61) times more likely to be obese compared to normal children; 1.39 (CI 1.31-1.47) times more likely to be obese if they had a high ponderal index,compared to normal children and 1.51 (CI 1.45-1.57) times more likely to be obese if they were BGA,compared to normal children. Using three different ways of measuring high weight of new born (macrosomic, BGA and high ponderal index) findings strongly suggest a direct relation between high weight and obesity of children at 6 years old.