NORMAL GROWTH: IN UTERO THROUGH PUBERTY
Human growth is characterized by a wide range of normals for height, weight, and growth velocity with each stage of life having a characteristic growth pattern and tempo, such as 1) dramatic fetal growth (the most rapid phase of human growth), 2) deceleration of growth immediately after birth, 3) a prolonged childhood phase, 4) prepubertal deceleration, and 4) a pronounced adolescent growth spurt.1 Adult height results from the degree to which genetic potential is realized, which depends on adequate nutrition and integration of hormonal and environmental factors.
Growth charts for height and weight are available from the US National Center for Health Statistics (NCHS) for ages birth to 36 months (Figures 31-1 and 31-2) and from ages 2 to 20 years (Figures 31-3 and 31-4) for both males and females. The growth charts were originally derived from a large cross-sectional sampling of children from North America and tend to flatten out the pubertal growth spurts. Children from other racial, ethnic, or geographical backgrounds may appear to grow different from the NCHS curves.
The North American growth charts developed by Tanner are derived from longitudinal data and are more useful for tracking pubertal development than are the NCHS growth curves.2 The Tanner growth charts include growth curves for early and late pubertal developers, spaces for tracking breast, pubic hair, and testicular development, as well as growth velocity standards.
In addition, a number of specialty growth curves are available for various syndromes such as Turner syndrome and conditions such as achondroplasia.
Fetal (Intrauterine) Growth
Intrauterine growth is regulated by a number of extrinsic and intrinsic factors.3 Fetal insulin is probably the single most important hormone effecting fetal size along with maternal insulin-like growth factor (IGF-I) and placental growth hormone (PGH). Fetal pituitary-derived growth hormone (pitGH) and fetal thyroid hormone are not particularly important in fetal growth, in marked contrast to their paramount roles in later life. Other growth factors that regulate intrauterine growth include fetal IGF-I and IGF-II, IGF binding protein 3, epidermal growth factor (EGF), fibroblast ...