CHILDREN BORN SMALL-FOR-GESTATIONAL-AGE - POSTNATAL-GROWTH AND HORMONAL STATUS

It is generally recognized that children born small-for-gestational ag e (SGA) have a 5-7 times higher risk of short stature than children bo rn at normal size. It has been suggested that the programming of the e ndocrine axes occurs during critical phases of fetal development and i s affected by intrauterine growth retardation. This study was undertak en to characterize the postnatal growth pattern and the final height o f children born SGA, as part of a population-based study (n = 3,650), from birth to final height, and to evaluate the hormonal status in ano ther group of prepubertal children born SGA (n = 134) without postnata l catch-up growth. The majority (88 %) of 'healthy' full-term singleto n SGA infants achieved catch-up growth during the first 2 years of lif e, and most of the increase in height occurred by 2 months of age. The SGA children who remained short at 2 years of age had a higher risk o f short stature later in life. The risk of having a short final height (<-2 SDS) was five times higher for children with a low birth weight and seven times higher for those with a low birth length in comparison with children with a normal birth size. Moreover, about 20% of all ch ildren of short stature were born SGA. As a group, children born SGA w ill have a final height, expressed in SDS, as they had during the prep ubertal years. This is in contrast to children, who became short postn atally. During puberty, these short children will have a mean height g ain of 0.6 SDS for girls and 0.7 SDS for boys. The mean estimated secr etion rate for growth hormone (GH) was lower in the short children bor n SGA compared with the reference groups born at an appropriate size f or gestational age, of either short (p < 0.05) or normal stature (p < 0.001). Moreover, in the youngest children born SGA (2-6 years of age) a different pattern of GH secretion was found, with a high basal GH l evel, low peak amplitude, and high peak frequency. The majority of the children born SGA had levels of GH-binding protein within the range p reviously reported for normal children. However, the levels of insulin -like growth factor I (IGF-I), IGF-binding protein-3 (IGFBP-3) and lep tin were significantly reduced compared with the reference values (p < 0.001, p < 0.01 and p < 0.001, respectively). In conclusion, the low spontaneous GH secretion rate and a disturbed GH secretion pattern, to gether with low serum levels of IGF-I, IGFBP-3 and leptin, might contr ibute to the reduced postnatal growth in some of the subgroup of child ren born SGA who remained short during childhood.