Context and objective: Low birth weight followed by rapid postnatal weight gain is associated with long-term risks for central obesity and insulin resistance. However, the timing of these changes is unclear.
Setting, design, and patients: This was a longitudinal cohort study in low birth weight (SGA; birth weight < -2 sd; n = 29) and normal birth weight (AGA; n = 22) children from Barcelona.
Main outcome measures: Body composition, by dual-energy x-ray absorptiometry scan, and insulin sensitivity, assessed longitudinally at ages 2, 3, and 4 yr, were measured.
Results: Mean height, weight, and body mass index at ages 2, 3, and 4 yr were not different between SGA and AGA children. At age 2 yr, SGA children had similar body composition but were more insulin sensitive than AGA children and had lower serum IGF-I levels and lower neutrophil counts. Between ages 2 and 4 yr, despite similar gains in weight and body mass index, SGA children gained more abdominal fat and body adiposity and less lean mass than AGA children; by age 4 yr, SGA children had greater adiposity, insulin resistance, and higher neutrophil counts than AGA children (P = 0.01-0.0004). In SGA children, total and abdominal fat mass at 4 yr was more closely related to rate of weight gain between 0 and 2 yr (P = 0.002-0.0003) than between 2 and 4 yr (P = 0.04-0.1).
Conclusion: Consequent to catch-up weight gain between birth and 2 yr, SGA children showed a dramatic transition toward central adiposity and insulin resistance between ages 2 and 4 yr. Understanding the mechanisms underlying this predisposition to adverse future health could lead to specific preventive interventions during early childhood.