Accelerated growth in early life and obesity in preschool Chilean children.

In Chile, childhood obesity rates are high. The purpose of this article is to compare BMI growth characteristics of normal (N), overweight (OW), and obese (OB) 5-year olds from 0 to 5 years and explore the influence of some prenatal factors on these patterns of growth. The study was done on a retrospective cohort of 1,089 5-year olds with birth weight >2,500 g. Weight and height were obtained from records at nine occasions (0-36 months); at 52 and 60 months, we measured them. At 60 months, children were classified as N, OW, and OB. At each age, BMI and z-score of BMI (BMI Z) differences were compared among groups. The influence of birth weight, pre-pregnancy BMI, and prenatal variables (weight gain, smoking, and presence of diabetes and preeclampsia) on BMI Z differences between N and OB was also explored. Adiposity rebound (AR) was not observed for the N, although for the OW, it occurred approximately 52 months and for the OB at approximately 24 months. BMI Z differences between N and OB were significant from birth, but were greatest between 6-12 and 36-52 months. Additional adjustment by birth weight, pre-pregnancy BMI, and prenatal variables decreased the BMI Z differences for the first 24 months with virtually no effect after this age. Accelerated growth in OB children from post-transition countries occurs immediately after birth, much earlier than the AR. The influence of prenatal factors on adiposity acquisition may extend at most until 2 years of life, although BMI gains thereafter are more related to postnatal variables.