Intrauterine growth retardation (IUGR) refers to fetal growth that has been constrained in utero. It results in newborns that have not attained their full growth potential and are already malnourished at birth. Fetuses that suffer from growth retardation have higher perinatal morbidity and mortality and are more likely to experience poor cognitive development and neurologic impairment during childhood. Research shows that as adults IUGR babies have increased risk of cardiovascular disease, high blood pressure, diabetes, and related diseases. Moreover, IUGR contributes to the cycle of malnutrition between generations. The implications of this cycle for both human and socioeconomic development of the affected populations are enormous. SITUATION IN THE DEVELOPING WORLD Human growth is defined as an increase in size over time, not only in the fetus, but throughout childhood until the time of skeletal fusion. Size at the time of birth, therefore, is a function of two factors: the rate of fetal growth and the duration of gestation. But because valid assessment of the duration of pregnancy is difficult to obtain in developing countries, the prevalence of low birth weight has been often used as a proxy to determine the magnitude of IUGR. The availability and quality of birth-weight data is also problematic. Despite these constraints, recent estimates suggest that currently about 11 percent of newborns, or 12.6 million infants, suffer from low birth weight at term (the IUGR proxy). The magnitude of the problem varies widely across countries and geographical regions (see table). Low birth weight at term is especially common in South Central Asia, where 21 percent of newborns are affected, accounting for about 64 percent of all affected newborns worldwide. Low birth weight at term is also common in Middle and Western Africa, but much less so in Latin America and the Caribbean. It is important to note that in the poorest developing countries, a large proportion of newborns, and not just those below an arbitrary cutoff point, are likely to suffer some degree of prenatal growth retardation.