Background: Low birth weight (BW) (<2,500 g) is associated with a high risk of impaired postnatal growth and late metabolic consequences. The aim of this study is to describe the postnatal growth pattern and the metabolic status of children born small for gestational age (SGA) and compare them with premature children born with low (1,500-2,500 g) and very low (<1,500 g) BW.
Children and methods: 104 prepubertal children (47 males and 57 females) aged 3.0 to 8.9 years were divided into four groups according to their birth weight adjusted for gestational age (GA): SGA-premature (SGApr): BW < -2 SD, GA <37 wk (n = 17); SGA-full-term (SGAt): BW < -2 SD, GA >37 wk (n = 29); low birth weight (LBW): BW = 1,500-2,500 g, GA <37 wk (n = 35); very low birth weight (VLBW): BW <1,500 g, GA <37 wk (n = 23). The control group consisted of 27 full-term appropriate for gestational age, prepubertal children matched for age. All children had anthropometric and laboratory measurements. The HOMA model was used to estimate insulin resistance (IR).
Results: Weight, height and body mass index (BMI) were significantly lower in the SGA groups -- both term and premature -- (p <0.05) and particularly lower in the VLBW children (p <0.01). At the age of 36 months, 99.6% of SGAt and a smaller percentage of SGApr (88.2%) children achieved catch-up growth. IGF-I and IGFBP-3 levels were lower in the children born SGA, both term and premature, compared to the controls (p <0.05) and especially in those who had catch-up after the age of 6 months (p <0.002). VLBW children aged 6-8.9 years had significantly higher HOMA compared to controls of the same age group (p = 0.005), whereas no evidence of IR was found in the SGA children. None of the children had developed premature adrenarche by the day of examination.
Conclusions: Prepubertal children born SGA and VLBW are thinner and shorter than their age-matched controls. A larger percentage of SGA full-term children achieve catch-up growth than SGA premature children by 3 years of age. SGA children and especially those with late catch-up growth have lower IGF-I levels. Children with VLBW show evidence of IR at age 6-8.9 years. None of the girls showed precocious sexual development by the day of examination.