Undernutrition during fetal and postnatal life is still a major problem in many low- and middle-income countries. Even in high-income countries malnutrition may exist in cases of intrauterine growth retardation, as well as in chronic conditions such as anorexia nervosa and inflammatory bowel disease. Children adopted from developing countries are often chronically malnourished. Nutritional rehabilitation, resulting in catch-up growth, is often complicated by influences originating in fetal life as well as during postnatal growth. This may result in hormonal and metabolic changes as well as alterations in pubertal development. The present review focuses on fetal, postnatal and fetal-postnatal undernutrition and subsequent catch-up growth as well as catch-up growth in relation to pubertal development. Catch-up growth in children can be associated with early puberty following fetal or combined fetal-postnatal undernutrition. However, early puberty does not seem to occur following catch-up growth after isolated postnatal undernutrition. Gonadotropins have been reported to be elevated in prepubertal adopted girls as well as during catch-up growth in animals. Even if other factors may contribute, linear catch-up growth seems to be associated with the timing of pubertal development. The mechanisms behind this are still unknown. Future research may elucidate how to carry out nutritional rehabilitation without risk for early pubertal development.
Keywords: adopted children; catch-up growth; early puberty; nutritional rehabilitation; stunting; undernutrition.